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The eternal question with overclocking is... Which tests and for how long does your system need to pass them for it to be deemed a 100% stable overclock? The di

The eternal question with overclocking is... Which tests and for how long does your system need to pass them for it to be deemed a 100% stable overclock? The different PC enthusiast communities and even individual posters within them all have different answers.

deleted 9y ago
[deleted]
paulmd 9y ago
If your system will handle 15-30m of Prime95 SmallFFT then you're pretty much good to go. Prime95 is real sensitive to instability and odds are good that if it's gonna crash it'll crash in the first 10 seconds. Beyond that, just pick your burner application of choice and let it run for an hour while you go watch a movie. The rest are all kinda interchangeable as far as I'm concerned. Aida64 maybe? (one note: I would not leave Prime95 running for prolonged periods of time. Modern CPUs are not designed for a program that is so small it fits into uop cache and runs AVX nonstop. With a heavy overclock it can pull 300W+ (potentially above 400W) on HEDT processors and OEMs like Asus have warned that it may cause damage[0]. Electromigration seems like a likely culprit meaning time is a key factor. Running Prime95 for like a half hour is fine and a great stability test, but 24H+ runs are extremely unnecessary and potentially damaging.) [0] https://rog.asus.com/articles/overclocking/rog-overclocking-guide-core-for-5960x-5930k-5820k/ https://rog.asus.com/articles/overclocking/rog-overclocking-... (Note that while this article is regarding Haswell-E, the same logic really applies to Broadwell-E as well as Ryzen 5 and 7. Running a processor at triple its nominal TDP nonstop for a prolonged period with most of that power going though a few specific execution units simply cannot be healthy for it.)
- deleted 9y ago
  [deleted]
- ComputerGuru 9y ago
  I'm curious as to your recommendation of SmallFFT in response to the grandparent's post. prime95, iirc, says SmallFFT does not test the RAM much. I think "blend mode" was the recommendation that includes RAM testing, while SmallFFT was more for stress-testing CPU overclocks? Is it because the question is not whether or not a particular bit of RAM is damaged and rather whether or not the overclock to the communications bus between CPU and RAM is affected?
  - paulmd 9y ago
    Yeah, blend is probably better if you're going for RAM overclocking. Which is really what's going on here. Or maybe something that's really hammering throughput or something (database loads come to mind). Obviously you want to focus your testing on whatever subsystem you're trying to OC. I was just giving generic advice on overclocking. There is pretty broad consensus that Prime95 is a good stability test for CPUs. Someone also suggested Intel Burn Test as a test that might catch some instabilities that Prime95 misses in a reply and then deleted it for some reason (why?). In particular though, it's not just the memory subsystem you're overclocking here, you're really overclocking the interconnect as well. It will have its own "silicon lottery" and a particular point of instability, in addition to your individual memory kit's own stability characteristics. There are a lot of moving parts here. I do wonder how much of this is getting the memory controller stable versus getting the interconnect stable. It seems possible they may have knobs they can twiddle on the interconnect as well. [Serious question here:] I wonder if Prime95 or burn-test type tools would stress the interconnect with enough cross-core communication to be worth running.
- porterhouseromp 9y ago
  > Prime95 is real sensitive to instability You mean 'really sensitive'. 'real' is the adjective form - 'really' is the adverb submodifier form, which is the one you want in this case.
  - d33 9y ago
    It's acceptable in colloquial sense: https://en.wiktionary.org/wiki/real#Adverb https://en.wiktionary.org/wiki/real#Adverb ; Also, I heard it's more common in some US states.
  - joshjje 9y ago
    Most of the time I dont use apostrophes.
- Terr_ 9y ago
  > If your system will handle 15-30m of Prime95 SmallFFT then you're pretty much good to go. Wait, SmallFFT? Isn't that the test that focuses heavily on CPU and very little on the memory? Since this news is about memory timings/overclocking, I'd rather put much more focus on tools like Memtest86+, running that for a few hours to be sure that it touches all the addressable regions and uses various access patterns. Whatever test you do, you want to exercise all the memory, or else you'll end up with a computer that always seems fine after boot, but accumulates errors and crashes based on uptime and how much concurrent work you throw at it.
  - Sephr 9y ago
    Memtest86+ tests the memory itself. I think Prime95 mixed mode is best if your goal is to stress the memory controller and all related subsystems.
    - Sephr 9y ago
      Update: I mean blend mode
- deleted 9y ago
  [deleted]
- ah- 9y ago
  Would Prime95 be likely to damage hardware if ran for a prolonged period on aws/gce/azure? Do they have anything in their contracts telling you not to do that?
  - deagle50 9y ago
    The hypervisor could throttle the workload even if it lit up the entire physical node (which is unlikely). The CPU could also throttle itself, the instances where Prime fried CPUs were due to overclockers forcing high frequencies and voltages AFAIK.
- gigatexal 9y ago
  Yup 24 hours of smallFFT or bust. And then a similar thing with any over clocked GPU.
- userbinator 9y ago
  Modern CPUs are not designed for a program that is so small it fits into uop cache and runs AVX nonstop. This is a slippery slope towards CPUs which are only warranted to run certain approved apps. Overclocking aside, I'd consider a CPU broken if it can't run any sequence of instructions 24/7 without damage at the stock speed and voltage. Besides, Prime95 isn't what I'd consider a pathological case anyway --- FFTs are common in scientific computing and signal processing, and having a CPU continuously perform them is not at all an unusual workload. It somewhat reminds me of https://news.ycombinator.com/item?id=7205759 https://news.ycombinator.com/item?id=7205759
  - eigenvector 9y ago
    I agree with you, but with the caveat that CPUs should be able to run flat-out, indefinitely at rated voltage. In this case, people are over-volting the CPU by up to 40% so running the hardest workloads simply pushes an amount of power (heat) through the CPU that it was never intended to handle.
    - deleted 9y ago
      [deleted]
  - gigatexal 9y ago
    The way I see it is an over clock is only stable if it can run the same applications as a stock clocked chip could at full bore for the same time periods. So if you could take a stock 4770k or something and run prime95 small FFTs albeit at 90C for 24 hours with no issues then your OC should as well. Having a high standard like that means I have more confidence in my OCs and my systems.
    - paulmd 9y ago
      > The way I see it is an over clock is only stable if it can run the same applications as a stock clocked chip could at full bore for the same time periods. AVX has been on a separate clock/offset for a while now, and many OC'ing motherboards will let you tweak it. Given how much power AVX consumes I wouldn't be surprised if throttling it even let you clock the rest of the core higher. > run prime95 small FFTs albeit at 90C for 24 hours with no issues then your OC should as well That's nice in theory but in practice if it's gonna crash it's gonna do it quick. I doubt many CPUs are suddenly erroring out for the first time at 23 hours. So why not just test for an hour and call it good? An hour of super abnormally high stress is more than enough to validate it for standard usage in my opinion. More than OK at 30 minutes too. Usually fails within the first 5 seconds, if you make it to 1 min then you have a very solid chance of making it the whole way. 30-60m is plenty. If your data assurance requirements exceed one "proof test" shot[0], so to speak, then you have no business using overclocked CPUs at all. Prime95 SmallFFT is way way more stress than you would ever put a CPU under in any real-world load, and like an overpressured proof shot it's not really the best thing in the world for the processor to do this nonstop. Electromigration is a thing that exists. [0] https://en.wikipedia.org/wiki/Proof_test https://en.wikipedia.org/wiki/Proof_test
- BoorishBears 9y ago
  I remember when I built my last gaming PC I unknowingly ran a version of Prime95 that could not pass an OC stress test on certain Intel processors. The combination of instructions it used meant that even if, under sustained 100% CPU load with a normal benchmark, your cooling solution was sufficient, within 30 seconds the CPU would hit 100° and activate it's thermal protection before a shutdown. I went through 3 water cooling setups and numerous thermal paste reapplications before I realized, since I was driving the CPU hard (4690k at 4.9Ghz with a high overvoltage I recall being considered at the limit for non-LN2 setups, 1.4?) and thought that cooling was the issue
zamalek 9y ago
This isn't exactly overclocking. Rephrased in terms of CPUs: it's as though motherboards always clocked the CPU to 2.1GHz, irrespective of what is indicated on the CPU box. This happens with RAM because there used to be no way for the RAM to advertise its speed and timings to the motherboard. Intel corrected this with XMP on their platform (I'm not sure what the AMD equivalent is called). If you clock your memory to its advertised speed and timings (i.e. enable the XMP profile) you ~~won't~~ [edit] shouldn't have any problems after booting. What may happen is that your system fails to POST, in which case you need a better motherboard. Using the correct memory profile is extremely important. Reviewers found that the performance of Ryzen is strongly correlated to the memory clock - something to do with Infinity Fabric. This means that DDR4-4000 is, in theory, absolutely required if you want the most out of Ryzen - making this patch a big deal for Ryzen users.
- AaronFriel 9y ago
  My understanding (please, someone tell me if I'm off base!) is that the infinity fabric is kind of like Intel's QuickPath Interconnect and the "uncore" in one. In Intel systems it was* required to have the uncore clock be twice the memory clock-rate. The "uncore" clock rate controlled the clock for caches, the memory controllers, possibly other IO components, and the like. It makes sense that certain benchmarks would be insensitive to increases in memory frequency if those same components were locked at ~2.1GHz in Ryzen's initial release. On a related note: does AMD publish block diagrams for their infinity fabric or is there any firm information about how many PCIe 3 lanes will be available on the Threadripper platform? * - I'm not sure if it still is, to be honest!
  - paulmd 9y ago
    > On a related note: does AMD publish block diagrams for their infinity fabric or is there any firm information about how many PCIe 3 lanes will be available on the Threadripper platform? I'm interested in a block diagram or documentation as well, if anyone knows of any. PcPer did some tests which show the inter-core latency and some other experimental data. https://www.pcper.com/reviews/Processors/AMD-Ryzen-and-Windows-10-Scheduler-No-Silver-Bullet https://www.pcper.com/reviews/Processors/AMD-Ryzen-and-Windo... > My understanding (please, someone tell me if I'm off base!) is that the infinity fabric is kind of like Intel's QuickPath Interconnect and the "uncore" in one. Yeah that sounds about right. The only thing I will add is that I've heard (can't source) inter-die communication on Threadripper/EPYC multi-chip-modules apparently happens by a different mechanism than intra-die/inter-CCX communication. As such, my suspicion is that Threadripper and EPYC will basically behave like a multi-socket system. As for lanes: I think it's official at this point that Threadripper has 44 lanes like Skylake-E does, and EPYC has 128 PCIe lanes. Possibly plus additional lanes from the PCH? https://arstechnica.com/gadgets/2017/05/amd-ryzen-threadripper-price-specs-release-date/ https://arstechnica.com/gadgets/2017/05/amd-ryzen-threadripp...
flamedoge 9y ago
I used to overclock a little, until I realized it's just killing the chip faster. These things are made to fail eventually but much later with stock clocks.
- paulmd 9y ago
  There are plenty of Sandy Bridge and FX processors that have been heavily OC'd since day 1 that are still ticking along five years later. If you have decent cooling and don't go too nuts on the voltage it's perfectly safe. And if your CPU dies after 5 years of hard labor do you really care all that much? FWIW I do agree with you though. I overclocked my 5820K to 4.13 GHz all-core, which is as far as it would go on stock voltages. According to the on-chip sensors I pull 90W during a normal (non-AVX) load. I could probably get another 400-500 MHz if I really pushed it, but getting the last 10% isn't worth turning that 90W processor into 200W+ for me. For scaredy-cats: I think that's a pretty reasonable approach to overclocking. Just go as far as you can at stock voltages. I bet pretty much any processor can overclock all its cores to max turbo speed with either no extra voltage or a very minor voltage increase.
  - flamedoge 9y ago
    There's really one need that warrants overclocking -- gaming. I realize I need my processor for other things and not fail at it. I can sip coffee awhile longer while it finishes the job.
    - sergers 9y ago
      A hobby :) Use to be a frequenter of extremesystems.org 10-15 years ago, in the overclocking and water-cooling threads. Good fun. Now practicality wise, I had no use to OC really. Wasn't even a big gamer at the time. Pure fully fun and just seeing if I could (thought I was the cool kid running water-cooling, overclocked cpu/mem/you, installing every nightly patch in Gentoo portage with a tonne of system specific gcc and kernel flags lol). Now my thousands of dollars water-cooling parts, and a q6600 processor have been sitting in garage for 10 years. Use a standard i7 low-end laptop, no desktops in past 10 years
strainer 9y ago
When I used to tweak settings to the max i found that even heavy testing was no guarantee of stability in following months or years. With the system set on the edge of stability it can pass heavy testing but still be super susceptible to slow degradation of silicon and electronics and to transient conditions. I like to set things quick and cool running these days - i do quite quick stress testing to find roughly the best voltage/speeds and then add buffers of 5-10% voltage and sacrifice 5-20% speed to help guarantee some years of stability.
- TrainedMonkey 9y ago
  That is why you back off from the bleeding edge after endurance testing it. I have not done overclocking for quite a while, but general strategy was: 0. Get the right hardware - some hardware oveclocks better. 1. Depending on what you overclock come up with a short stress test. This would be GPU/CPU/RAM/PSU testing. 2. One component at a time. Identify top voltage/temp you are willing to tolerate. Overlock in steps of 5-10% nominal frequency. When the stress test fails increase the voltage by 5-10% until you reach the voltage limit. Once you get all of the data look at the frequency voltage curve and pick a voltage point (generally lower is better), back off a step or two from the frequency that passed and run an endurance test. 3. Run all components at the same time and stress test the entire system. The caveats here are to look out for power and temperature issues. I.E. make sure nothing get too hot (this includes the motherboard power regulators!) or voltage rails drop out of spec. 4. Slightly back off from the setup that passed 3 and you should be good to go for long term usage. TL-DR: Overclock one component at a time come up with frequency/max temp/required voltage chart and don't try to run the hardware on the bleeding edge. edit: list spacing...
  - strainer 9y ago
    I thought I was rock stable after lots of testing in one case, memtest, prime95, 'stability test' even thrashed the floppy drive. Later i wrote a java applet that hit the cpu cores in both regular and random millisecond patterns - it crashed the machine in seconds. Multicore load effects are something else to look out for then - take a few steps back from the edge and it all matters much less. Its worth it for a solid machine.
userbinator 9y ago
My choice of stability test is Intel Linpack, although it probably doesn't work so well on AMD CPUs; and my rule is that a system which can't survive at least 24h of Linpack is not stable --- I've seen systems fail it with stock voltages and frequencies. I used to overclock, but stopped after realising the errors that occurred with Linpack; it really made me appreciate the fact that a CPU could miscalculate, and a system that appears "stable" can actually be silently corrupting data.
floatboth 9y ago
Grand Theft Auto IV. No, seriously — it crashed my CPU (i5-6400) at 4.5GHz when linpack finished just fine at these settings. Lowered to 4.4 and no more crashes.
std_throwaway 9y ago
There is no easy answer. My approach would be something like this: * Take 100 identical machines and run them with a specific setting for a year. Take the number of failures and write it down. * Take another 100 machines and run them with a different settings for a year. Write down the failures. * Do this for like 10 different speed settings. (You need 1000 machines and have to wait one year of time.) * Make a graph of the data. Log of failures over linear speed axis. * Try to see a curve in the graphed data. * Determine the failure rate that you want to achieve. * Look up the speed setting in the curve. * Now you have your speed. I guess only people like the processor manufacturers actually do it this way. Most other folks just do guesswork. If you have advanced knowledge about the failure curve you might come up with a law like this: * Turn up the speed until you hit 1 failure per 24 hours under heavy load. * Turn down the speed by 30% and sell.
ionised 9y ago
I'd say an overnight test (around 8 hours) is enough. Do this for Memtest86+ and Prime95/OCCT/Intel Burn. Contrary to some opinions I've seen, playing a game for a while is not a sufficient test for overclock stability.

deleted 9y ago

[deleted]

paulmd 9y ago

If your system will handle 15-30m of Prime95 SmallFFT then you're pretty much good to go. Prime95 is real sensitive to instability and odds are good that if it's gonna crash it'll crash in the first 10 seconds. Beyond that, just pick your burner application of choice and let it run for an hour while you go watch a movie. The rest are all kinda interchangeable as far as I'm concerned. Aida64 maybe? (one note: I would not leave Prime95 running for prolonged periods of time. Modern CPUs are not designed for a program that is so small it fits into uop cache and runs AVX nonstop. With a heavy overclock it can pull 300W+ (potentially above 400W) on HEDT processors and OEMs like Asus have warned that it may cause damage[0]. Electromigration seems like a likely culprit meaning time is a key factor. Running Prime95 for like a half hour is fine and a great stability test, but 24H+ runs are extremely unnecessary and potentially damaging.) [0] https://rog.asus.com/articles/overclocking/rog-overclocking-guide-core-for-5960x-5930k-5820k/ https://rog.asus.com/articles/overclocking/rog-overclocking-... (Note that while this article is regarding Haswell-E, the same logic really applies to Broadwell-E as well as Ryzen 5 and 7. Running a processor at triple its nominal TDP nonstop for a prolonged period with most of that power going though a few specific execution units simply cannot be healthy for it.)

deleted 9y ago
[deleted]
ComputerGuru 9y ago
I'm curious as to your recommendation of SmallFFT in response to the grandparent's post. prime95, iirc, says SmallFFT does not test the RAM much. I think "blend mode" was the recommendation that includes RAM testing, while SmallFFT was more for stress-testing CPU overclocks? Is it because the question is not whether or not a particular bit of RAM is damaged and rather whether or not the overclock to the communications bus between CPU and RAM is affected?
- paulmd 9y ago
  Yeah, blend is probably better if you're going for RAM overclocking. Which is really what's going on here. Or maybe something that's really hammering throughput or something (database loads come to mind). Obviously you want to focus your testing on whatever subsystem you're trying to OC. I was just giving generic advice on overclocking. There is pretty broad consensus that Prime95 is a good stability test for CPUs. Someone also suggested Intel Burn Test as a test that might catch some instabilities that Prime95 misses in a reply and then deleted it for some reason (why?). In particular though, it's not just the memory subsystem you're overclocking here, you're really overclocking the interconnect as well. It will have its own "silicon lottery" and a particular point of instability, in addition to your individual memory kit's own stability characteristics. There are a lot of moving parts here. I do wonder how much of this is getting the memory controller stable versus getting the interconnect stable. It seems possible they may have knobs they can twiddle on the interconnect as well. [Serious question here:] I wonder if Prime95 or burn-test type tools would stress the interconnect with enough cross-core communication to be worth running.
porterhouseromp 9y ago
> Prime95 is real sensitive to instability You mean 'really sensitive'. 'real' is the adjective form - 'really' is the adverb submodifier form, which is the one you want in this case.
- d33 9y ago
  It's acceptable in colloquial sense: https://en.wiktionary.org/wiki/real#Adverb https://en.wiktionary.org/wiki/real#Adverb ; Also, I heard it's more common in some US states.
- joshjje 9y ago
  Most of the time I dont use apostrophes.
Terr_ 9y ago
> If your system will handle 15-30m of Prime95 SmallFFT then you're pretty much good to go. Wait, SmallFFT? Isn't that the test that focuses heavily on CPU and very little on the memory? Since this news is about memory timings/overclocking, I'd rather put much more focus on tools like Memtest86+, running that for a few hours to be sure that it touches all the addressable regions and uses various access patterns. Whatever test you do, you want to exercise all the memory, or else you'll end up with a computer that always seems fine after boot, but accumulates errors and crashes based on uptime and how much concurrent work you throw at it.
- Sephr 9y ago
  Memtest86+ tests the memory itself. I think Prime95 mixed mode is best if your goal is to stress the memory controller and all related subsystems.
  - Sephr 9y ago
    Update: I mean blend mode
deleted 9y ago
[deleted]
ah- 9y ago
Would Prime95 be likely to damage hardware if ran for a prolonged period on aws/gce/azure? Do they have anything in their contracts telling you not to do that?
- deagle50 9y ago
  The hypervisor could throttle the workload even if it lit up the entire physical node (which is unlikely). The CPU could also throttle itself, the instances where Prime fried CPUs were due to overclockers forcing high frequencies and voltages AFAIK.
gigatexal 9y ago
Yup 24 hours of smallFFT or bust. And then a similar thing with any over clocked GPU.
userbinator 9y ago
Modern CPUs are not designed for a program that is so small it fits into uop cache and runs AVX nonstop. This is a slippery slope towards CPUs which are only warranted to run certain approved apps. Overclocking aside, I'd consider a CPU broken if it can't run any sequence of instructions 24/7 without damage at the stock speed and voltage. Besides, Prime95 isn't what I'd consider a pathological case anyway --- FFTs are common in scientific computing and signal processing, and having a CPU continuously perform them is not at all an unusual workload. It somewhat reminds me of https://news.ycombinator.com/item?id=7205759 https://news.ycombinator.com/item?id=7205759
- eigenvector 9y ago
  I agree with you, but with the caveat that CPUs should be able to run flat-out, indefinitely at rated voltage. In this case, people are over-volting the CPU by up to 40% so running the hardest workloads simply pushes an amount of power (heat) through the CPU that it was never intended to handle.
  - deleted 9y ago
    [deleted]
- gigatexal 9y ago
  The way I see it is an over clock is only stable if it can run the same applications as a stock clocked chip could at full bore for the same time periods. So if you could take a stock 4770k or something and run prime95 small FFTs albeit at 90C for 24 hours with no issues then your OC should as well. Having a high standard like that means I have more confidence in my OCs and my systems.
  - paulmd 9y ago
    > The way I see it is an over clock is only stable if it can run the same applications as a stock clocked chip could at full bore for the same time periods. AVX has been on a separate clock/offset for a while now, and many OC'ing motherboards will let you tweak it. Given how much power AVX consumes I wouldn't be surprised if throttling it even let you clock the rest of the core higher. > run prime95 small FFTs albeit at 90C for 24 hours with no issues then your OC should as well That's nice in theory but in practice if it's gonna crash it's gonna do it quick. I doubt many CPUs are suddenly erroring out for the first time at 23 hours. So why not just test for an hour and call it good? An hour of super abnormally high stress is more than enough to validate it for standard usage in my opinion. More than OK at 30 minutes too. Usually fails within the first 5 seconds, if you make it to 1 min then you have a very solid chance of making it the whole way. 30-60m is plenty. If your data assurance requirements exceed one "proof test" shot[0], so to speak, then you have no business using overclocked CPUs at all. Prime95 SmallFFT is way way more stress than you would ever put a CPU under in any real-world load, and like an overpressured proof shot it's not really the best thing in the world for the processor to do this nonstop. Electromigration is a thing that exists. [0] https://en.wikipedia.org/wiki/Proof_test https://en.wikipedia.org/wiki/Proof_test
BoorishBears 9y ago
I remember when I built my last gaming PC I unknowingly ran a version of Prime95 that could not pass an OC stress test on certain Intel processors. The combination of instructions it used meant that even if, under sustained 100% CPU load with a normal benchmark, your cooling solution was sufficient, within 30 seconds the CPU would hit 100° and activate it's thermal protection before a shutdown. I went through 3 water cooling setups and numerous thermal paste reapplications before I realized, since I was driving the CPU hard (4690k at 4.9Ghz with a high overvoltage I recall being considered at the limit for non-LN2 setups, 1.4?) and thought that cooling was the issue

zamalek 9y ago

This isn't exactly overclocking. Rephrased in terms of CPUs: it's as though motherboards always clocked the CPU to 2.1GHz, irrespective of what is indicated on the CPU box. This happens with RAM because there used to be no way for the RAM to advertise its speed and timings to the motherboard. Intel corrected this with XMP on their platform (I'm not sure what the AMD equivalent is called). If you clock your memory to its advertised speed and timings (i.e. enable the XMP profile) you ~~won't~~ [edit] shouldn't have any problems after booting. What may happen is that your system fails to POST, in which case you need a better motherboard. Using the correct memory profile is extremely important. Reviewers found that the performance of Ryzen is strongly correlated to the memory clock - something to do with Infinity Fabric. This means that DDR4-4000 is, in theory, absolutely required if you want the most out of Ryzen - making this patch a big deal for Ryzen users.

AaronFriel 9y ago
My understanding (please, someone tell me if I'm off base!) is that the infinity fabric is kind of like Intel's QuickPath Interconnect and the "uncore" in one. In Intel systems it was* required to have the uncore clock be twice the memory clock-rate. The "uncore" clock rate controlled the clock for caches, the memory controllers, possibly other IO components, and the like. It makes sense that certain benchmarks would be insensitive to increases in memory frequency if those same components were locked at ~2.1GHz in Ryzen's initial release. On a related note: does AMD publish block diagrams for their infinity fabric or is there any firm information about how many PCIe 3 lanes will be available on the Threadripper platform? * - I'm not sure if it still is, to be honest!
- paulmd 9y ago
  > On a related note: does AMD publish block diagrams for their infinity fabric or is there any firm information about how many PCIe 3 lanes will be available on the Threadripper platform? I'm interested in a block diagram or documentation as well, if anyone knows of any. PcPer did some tests which show the inter-core latency and some other experimental data. https://www.pcper.com/reviews/Processors/AMD-Ryzen-and-Windows-10-Scheduler-No-Silver-Bullet https://www.pcper.com/reviews/Processors/AMD-Ryzen-and-Windo... > My understanding (please, someone tell me if I'm off base!) is that the infinity fabric is kind of like Intel's QuickPath Interconnect and the "uncore" in one. Yeah that sounds about right. The only thing I will add is that I've heard (can't source) inter-die communication on Threadripper/EPYC multi-chip-modules apparently happens by a different mechanism than intra-die/inter-CCX communication. As such, my suspicion is that Threadripper and EPYC will basically behave like a multi-socket system. As for lanes: I think it's official at this point that Threadripper has 44 lanes like Skylake-E does, and EPYC has 128 PCIe lanes. Possibly plus additional lanes from the PCH? https://arstechnica.com/gadgets/2017/05/amd-ryzen-threadripper-price-specs-release-date/ https://arstechnica.com/gadgets/2017/05/amd-ryzen-threadripp...

flamedoge 9y ago

I used to overclock a little, until I realized it's just killing the chip faster. These things are made to fail eventually but much later with stock clocks.

paulmd 9y ago
There are plenty of Sandy Bridge and FX processors that have been heavily OC'd since day 1 that are still ticking along five years later. If you have decent cooling and don't go too nuts on the voltage it's perfectly safe. And if your CPU dies after 5 years of hard labor do you really care all that much? FWIW I do agree with you though. I overclocked my 5820K to 4.13 GHz all-core, which is as far as it would go on stock voltages. According to the on-chip sensors I pull 90W during a normal (non-AVX) load. I could probably get another 400-500 MHz if I really pushed it, but getting the last 10% isn't worth turning that 90W processor into 200W+ for me. For scaredy-cats: I think that's a pretty reasonable approach to overclocking. Just go as far as you can at stock voltages. I bet pretty much any processor can overclock all its cores to max turbo speed with either no extra voltage or a very minor voltage increase.
- flamedoge 9y ago
  There's really one need that warrants overclocking -- gaming. I realize I need my processor for other things and not fail at it. I can sip coffee awhile longer while it finishes the job.
  - sergers 9y ago
    A hobby :) Use to be a frequenter of extremesystems.org 10-15 years ago, in the overclocking and water-cooling threads. Good fun. Now practicality wise, I had no use to OC really. Wasn't even a big gamer at the time. Pure fully fun and just seeing if I could (thought I was the cool kid running water-cooling, overclocked cpu/mem/you, installing every nightly patch in Gentoo portage with a tonne of system specific gcc and kernel flags lol). Now my thousands of dollars water-cooling parts, and a q6600 processor have been sitting in garage for 10 years. Use a standard i7 low-end laptop, no desktops in past 10 years

strainer 9y ago

When I used to tweak settings to the max i found that even heavy testing was no guarantee of stability in following months or years. With the system set on the edge of stability it can pass heavy testing but still be super susceptible to slow degradation of silicon and electronics and to transient conditions. I like to set things quick and cool running these days - i do quite quick stress testing to find roughly the best voltage/speeds and then add buffers of 5-10% voltage and sacrifice 5-20% speed to help guarantee some years of stability.

TrainedMonkey 9y ago
That is why you back off from the bleeding edge after endurance testing it. I have not done overclocking for quite a while, but general strategy was: 0. Get the right hardware - some hardware oveclocks better. 1. Depending on what you overclock come up with a short stress test. This would be GPU/CPU/RAM/PSU testing. 2. One component at a time. Identify top voltage/temp you are willing to tolerate. Overlock in steps of 5-10% nominal frequency. When the stress test fails increase the voltage by 5-10% until you reach the voltage limit. Once you get all of the data look at the frequency voltage curve and pick a voltage point (generally lower is better), back off a step or two from the frequency that passed and run an endurance test. 3. Run all components at the same time and stress test the entire system. The caveats here are to look out for power and temperature issues. I.E. make sure nothing get too hot (this includes the motherboard power regulators!) or voltage rails drop out of spec. 4. Slightly back off from the setup that passed 3 and you should be good to go for long term usage. TL-DR: Overclock one component at a time come up with frequency/max temp/required voltage chart and don't try to run the hardware on the bleeding edge. edit: list spacing...
- strainer 9y ago
  I thought I was rock stable after lots of testing in one case, memtest, prime95, 'stability test' even thrashed the floppy drive. Later i wrote a java applet that hit the cpu cores in both regular and random millisecond patterns - it crashed the machine in seconds. Multicore load effects are something else to look out for then - take a few steps back from the edge and it all matters much less. Its worth it for a solid machine.

userbinator 9y ago

My choice of stability test is Intel Linpack, although it probably doesn't work so well on AMD CPUs; and my rule is that a system which can't survive at least 24h of Linpack is not stable --- I've seen systems fail it with stock voltages and frequencies. I used to overclock, but stopped after realising the errors that occurred with Linpack; it really made me appreciate the fact that a CPU could miscalculate, and a system that appears "stable" can actually be silently corrupting data.

floatboth 9y ago

Grand Theft Auto IV. No, seriously — it crashed my CPU (i5-6400) at 4.5GHz when linpack finished just fine at these settings. Lowered to 4.4 and no more crashes.

std_throwaway 9y ago

There is no easy answer. My approach would be something like this: * Take 100 identical machines and run them with a specific setting for a year. Take the number of failures and write it down. * Take another 100 machines and run them with a different settings for a year. Write down the failures. * Do this for like 10 different speed settings. (You need 1000 machines and have to wait one year of time.) * Make a graph of the data. Log of failures over linear speed axis. * Try to see a curve in the graphed data. * Determine the failure rate that you want to achieve. * Look up the speed setting in the curve. * Now you have your speed. I guess only people like the processor manufacturers actually do it this way. Most other folks just do guesswork. If you have advanced knowledge about the failure curve you might come up with a law like this: * Turn up the speed until you hit 1 failure per 24 hours under heavy load. * Turn down the speed by 30% and sell.

ionised 9y ago

I'd say an overnight test (around 8 hours) is enough. Do this for Memtest86+ and Prime95/OCCT/Intel Burn. Contrary to some opinions I've seen, playing a game for a while is not a sufficient test for overclock stability.