6 ms·

280 Watts TDP! Wow, I think that's a new record for desktop CPUs, although GPUs had reached that a while ago. I wonder how well air coolers work on them, or do

by jotm 7y ago

280 Watts TDP! Wow, I think that's a new record for desktop CPUs, although GPUs had reached that a while ago. I wonder how well air coolers work on them, or do they need water cooling for maximum performance? Impressive nonetheless.

pizza234 7y ago
Yes, they need water cooling. The marketing communication is amusing: "Optimized for water cooling": https://images.anandtech.com/doci/15062/AMD%20Fall%20Desktop%20Announcement%20Briefing%20Deck-page-008_575px.jpg https://images.anandtech.com/doci/15062/AMD%20Fall%20Desktop... Threadrippers are at least HEDT; I think this TDP is not unusual. Paradoxically, AMD's marketing is likely more reliable when they specify that the i9-9920X wall power consumption is up to ~300W (https://images.anandtech.com/doci/15062/AMD%20Fall%20Desktop%20Announcement%20Briefing%20Deck-page-007_575px.jpg https://images.anandtech.com/doci/15062/AMD%20Fall%20Desktop...), rather than Intel's own spec (https://www.intel.com.au/content/www/au/en/products/processors/core/x-series/i9-9920x.html https://www.intel.com.au/content/www/au/en/products/processo...).
- Someone1234 7y ago
  > Yes, they need water cooling. That's inaccurate. Air cooling solutions are readily available for Threadripper. Water cooling systems simply move heat to a more convenient place to air cool it away (thus the radiators and fans at the destination). The only limiter on air cooling (and not water) is weight/size on the CPU socket (or amount of air moving over the fins of the heatsinks). Some examples of retail air coolers that can cool it out of the box already: https://www.amd.com/en/thermal-solutions-threadripper https://www.amd.com/en/thermal-solutions-threadripper https://noctua.at/en/amd_ryzen_threadripper_tdp_guidelines https://noctua.at/en/amd_ryzen_threadripper_tdp_guidelines https://www.coolermaster.com/catalog/coolers/cpu-air-coolers/wraith-ripper/ https://www.coolermaster.com/catalog/coolers/cpu-air-coolers... Now the hypothetical ceiling on water cooling is of undeniably higher. You could literally use a jet engine as a fan to cool the water, or send it through liquid nitrogen. But we aren't there yet with 280 Watts. At the current wattage air cooling remains viable, with some trade-offs (e.g. huge air coolers, requiring huge cases, plus strong in-case airflow). You definitely don't "need water cooling," yet. At least not for threadripper.
  - Angostura 7y ago
    That's like saying that heat sinks 'don't make sense' Water cooling systems allow heat to be moved away from the chip's surface more efficiently than pointing at can at it can. Once moved away, a larger radiating surface can be air-coooled
  - the8472 7y ago
    > That's inaccurate and doesn't actually make sense. You want a steep temperature gradient at the limited chip surface to maximize heat flux. Pumping a liquid with high heat capacity to it steepens the gradient where you need it. Cooling the liquid on the other hand can happen over a much larger surface area with shallower gradients and thus lower heat flux. Note that while the heat pipes in air coolers do use convection they do so passively, liquid cooling solutions are active.
    - Someone1234 7y ago
      You've not really added anything to the discussion here, but seem to be using verbose language in an attempt to convey expertise. For example this: > You want a steep temperature gradient at the limited chip surface to maximize heat flux. Is true with both and is really just a convoluted way of saying "if you don't convect heat fast enough, it won't work." Yeah, undeniably true... > Pumping a liquid with high heat capacity to it steepens the gradient where you need it. Where you need it is at the surface of the CPU package. Both solutions provide adequate heat capacities at that location, that's why they fundamentally work. One uses heat pipes and fins directly above with fans/air carrying the heat away, the other moves the heat, and does the same elsewhere. > Cooling the liquid on the other hand can happen over a much larger surface area with shallower gradients and thus lower heat flux. Note that while the heat pipes in air coolers do use convection they do so passively, liquid cooling solutions are active. This is a basic explanation of how water cooling works, it doesn't really add any specific insight into the problem scope.
      - deleted 7y ago
        [deleted]
      - 7y ago
- jotm 7y ago
  "Recommended". So at least they're being honest, unlike Intel and their stated TDP. Laptop manufacturers have always used the cheapest possible cooling, but since Sandy Bridge, it has become painfully obvious the TDP is severely understated. Thermal throttling has become acceptable, and while it's impressive that Intel CPUs last years at ~90 degC, I'd rather they be honest with their actual requirements to get the full performance out of a given chip. Many laptops go over 90 degrees even at the guaranteed base speeds (no TurboBoost), in everyday use, not even multihour rendering or anything.
londons_explore 7y ago
I think TDP is becoming less and less of a comparable figure. All designs could use far more power in specific worst case corner cases (eg. a very specific instruction stream that causes every functional unit to be in use every cycle, and all data paths to toggle logic state every cycle). Yet in the typical use case (desktop PC, most cores idle most of the time), power consumption will be far lower. What really matters is the graph of "how much computation can I get out of this thing in 10ms bursts, 1 second bursts, and 10 minute bursts?", with a specific cooling setup.
- x3ro 7y ago
  I'm not sure whether people use $2k CPUs in "most of the time all cores are idle" scenarios a lot.
  - concerned_user 7y ago
    Even if they don't, 10-15% performance gain for double the price seems questionable. If you include the specialized motherboard, chillers, high speed ram even more so. Maybe in some very specific scenarios it would work like some VR prototype or flight sim, but for majority of users it doesn't make economic sense.
- pizza234 7y ago
  It's correct that TDP is getting more relative¹, but it's not correct that we're talking of corner cases. Anandtech locked an i9-9900k to 95W, and the loss was considerable (between 8 and 28%)². ¹: it needs to be noted that in the last years, Intel's TDP is getting "much more relative" than AMD's ²: https://www.anandtech.com/show/13591/the-intel-core-i9-9900k-at-95w-fixing-the-power-for-sff/9 https://www.anandtech.com/show/13591/the-intel-core-i9-9900k...
  - pingyong 7y ago
    Intel TDP always had the same meaning: "If your cooler can dissipate TDP, the CPU will run all-core loads at base clock speed, or a single-core loads at boost-clock speed." - Pretty sure that statement has always been true, within +- 100 MHz depending on the specific workload. The distance between base and boost clocks has just increased over the years.

by jotm 7y ago

pizza234 7y ago

Yes, they need water cooling. The marketing communication is amusing: "Optimized for water cooling": https://images.anandtech.com/doci/15062/AMD%20Fall%20Desktop%20Announcement%20Briefing%20Deck-page-008_575px.jpg https://images.anandtech.com/doci/15062/AMD%20Fall%20Desktop... Threadrippers are at least HEDT; I think this TDP is not unusual. Paradoxically, AMD's marketing is likely more reliable when they specify that the i9-9920X wall power consumption is up to ~300W (https://images.anandtech.com/doci/15062/AMD%20Fall%20Desktop%20Announcement%20Briefing%20Deck-page-007_575px.jpg https://images.anandtech.com/doci/15062/AMD%20Fall%20Desktop...), rather than Intel's own spec (https://www.intel.com.au/content/www/au/en/products/processors/core/x-series/i9-9920x.html https://www.intel.com.au/content/www/au/en/products/processo...).

Someone1234 7y ago
> Yes, they need water cooling. That's inaccurate. Air cooling solutions are readily available for Threadripper. Water cooling systems simply move heat to a more convenient place to air cool it away (thus the radiators and fans at the destination). The only limiter on air cooling (and not water) is weight/size on the CPU socket (or amount of air moving over the fins of the heatsinks). Some examples of retail air coolers that can cool it out of the box already: https://www.amd.com/en/thermal-solutions-threadripper https://www.amd.com/en/thermal-solutions-threadripper https://noctua.at/en/amd_ryzen_threadripper_tdp_guidelines https://noctua.at/en/amd_ryzen_threadripper_tdp_guidelines https://www.coolermaster.com/catalog/coolers/cpu-air-coolers/wraith-ripper/ https://www.coolermaster.com/catalog/coolers/cpu-air-coolers... Now the hypothetical ceiling on water cooling is of undeniably higher. You could literally use a jet engine as a fan to cool the water, or send it through liquid nitrogen. But we aren't there yet with 280 Watts. At the current wattage air cooling remains viable, with some trade-offs (e.g. huge air coolers, requiring huge cases, plus strong in-case airflow). You definitely don't "need water cooling," yet. At least not for threadripper.
- Angostura 7y ago
  That's like saying that heat sinks 'don't make sense' Water cooling systems allow heat to be moved away from the chip's surface more efficiently than pointing at can at it can. Once moved away, a larger radiating surface can be air-coooled
- the8472 7y ago
  > That's inaccurate and doesn't actually make sense. You want a steep temperature gradient at the limited chip surface to maximize heat flux. Pumping a liquid with high heat capacity to it steepens the gradient where you need it. Cooling the liquid on the other hand can happen over a much larger surface area with shallower gradients and thus lower heat flux. Note that while the heat pipes in air coolers do use convection they do so passively, liquid cooling solutions are active.
  - Someone1234 7y ago
    You've not really added anything to the discussion here, but seem to be using verbose language in an attempt to convey expertise. For example this: > You want a steep temperature gradient at the limited chip surface to maximize heat flux. Is true with both and is really just a convoluted way of saying "if you don't convect heat fast enough, it won't work." Yeah, undeniably true... > Pumping a liquid with high heat capacity to it steepens the gradient where you need it. Where you need it is at the surface of the CPU package. Both solutions provide adequate heat capacities at that location, that's why they fundamentally work. One uses heat pipes and fins directly above with fans/air carrying the heat away, the other moves the heat, and does the same elsewhere. > Cooling the liquid on the other hand can happen over a much larger surface area with shallower gradients and thus lower heat flux. Note that while the heat pipes in air coolers do use convection they do so passively, liquid cooling solutions are active. This is a basic explanation of how water cooling works, it doesn't really add any specific insight into the problem scope.
    - deleted 7y ago
      [deleted]
    - 7y ago
jotm 7y ago
"Recommended". So at least they're being honest, unlike Intel and their stated TDP. Laptop manufacturers have always used the cheapest possible cooling, but since Sandy Bridge, it has become painfully obvious the TDP is severely understated. Thermal throttling has become acceptable, and while it's impressive that Intel CPUs last years at ~90 degC, I'd rather they be honest with their actual requirements to get the full performance out of a given chip. Many laptops go over 90 degrees even at the guaranteed base speeds (no TurboBoost), in everyday use, not even multihour rendering or anything.

londons_explore 7y ago

I think TDP is becoming less and less of a comparable figure. All designs could use far more power in specific worst case corner cases (eg. a very specific instruction stream that causes every functional unit to be in use every cycle, and all data paths to toggle logic state every cycle). Yet in the typical use case (desktop PC, most cores idle most of the time), power consumption will be far lower. What really matters is the graph of "how much computation can I get out of this thing in 10ms bursts, 1 second bursts, and 10 minute bursts?", with a specific cooling setup.

x3ro 7y ago
I'm not sure whether people use $2k CPUs in "most of the time all cores are idle" scenarios a lot.
- concerned_user 7y ago
  Even if they don't, 10-15% performance gain for double the price seems questionable. If you include the specialized motherboard, chillers, high speed ram even more so. Maybe in some very specific scenarios it would work like some VR prototype or flight sim, but for majority of users it doesn't make economic sense.
pizza234 7y ago
It's correct that TDP is getting more relative¹, but it's not correct that we're talking of corner cases. Anandtech locked an i9-9900k to 95W, and the loss was considerable (between 8 and 28%)². ¹: it needs to be noted that in the last years, Intel's TDP is getting "much more relative" than AMD's ²: https://www.anandtech.com/show/13591/the-intel-core-i9-9900k-at-95w-fixing-the-power-for-sff/9 https://www.anandtech.com/show/13591/the-intel-core-i9-9900k...
- pingyong 7y ago
  Intel TDP always had the same meaning: "If your cooler can dissipate TDP, the CPU will run all-core loads at base clock speed, or a single-core loads at boost-clock speed." - Pretty sure that statement has always been true, within +- 100 MHz depending on the specific workload. The distance between base and boost clocks has just increased over the years.