5 ms·

Wait, undervolting improves game performance for you?

• booi 6y ago
  hmm maybe less thermal throttling?
  • philjohn 6y ago
    And hitting higher clocks, for longer, as a result.
• Doxin 6y ago
  Might avoid hitting a thermal threshold and downclocking.
• freeqaz 6y ago
  Yes, definitely! Your laptop is generally constrained by how much heat it can push through the heat sink. If you get "lucky" you have a CPU that can remain stable at lower voltages. So it's effectively the same as an "overclock" because your laptop can turbo the core speed up for longer (or forever). Your laptop rarely runs at maximum turbo all day. It can only do that for a few hundred ms usually. It'll basically just hold the clock speed at whatever it can before hitting some specific temp (85-95c). When you undervolt, the frequency that it can "hold" at that temp threshold is higher.
  • neltnerb 6y ago
    Yeah, even with my NUC that had a pretty decent fan running at top speed I literally put a block of metal I kept in the freezer on top of it to keep it from downthrottling due to overheating. It was ridiculous that it could let itself get that hot instead of doing something more graceful.
    • copperx 6y ago
      Please share the name of the NUC so others can avoid it.
      • neltnerb 6y ago
        It's a 5th generation core i7 in the Intel NUC. It's been off the market for four years and the thermal issues were known and addressed in the intervening years to the best of my understanding. I'm just saying that linux does not do a great job of gracefully limiting CPU power to avoid a lower BIOS level limiter kicking in and performing worse than if it just throttled down a bit earlier.
  • Geee 6y ago
    I wonder what exactly causes "instability" when overclocking/undervolting in a processor. Transistors don't have enough time to switch, but it matters where it happens. If there's an error in e.g. floating-point unit, it would just cause random errors in the output, but the game would probably keep running. That might be completely fine, if it's rare and you could undervolt just that unit a lot. Especially in somewhere in the graphics pipeline, where it would just generate visual noise. Also, I think energy consumed / heat is proportional to voltage squared, so it has a big effect.
    • SomeoneFromCA 6y ago
      Lower voltage slows down recharging of the gates. Bugs in the integrated graphics can easily lock up the whole thing.
    • kalium-xyz 6y ago
      Afaik impurities, small imperfections, and micro fractures increase resistance which increases power consumption and generate heat. Im not an expert on this but I assume even how well the chip was soldered to the board might make a serious difference here.
    • avianes 6y ago
      > If there's an error in e.g. floating-point unit, it would just cause random errors in the output, but the game would probably keep running The processor circuitry does not only consist of transistors dedicated to the datapath, a significant amount of transistors are used to control the datapath. If control transistors are faulty there is no guarantee about the processor behavior. Also, I don't know about Intel cpu protections, but in modern secure hardware we include dedicated circuits for power/clock glitch detection. The glitch detection circuit is designed with a higher sensibility to power/clock fault than the rest of the circuit, this way its avoids that clock/power faults affect the integrity of the circuit output.
    • geogriffin 6y ago
      The Plundervolt [1] paper is one study in what exactly goes haywire when a processor is undervolted. They found that the computation errors induced are quite consistent and reproducible. MUL and DIV are vulnerable, and AES-NI happened to be particularly badly broken in the face of undervolting. [1] https://plundervolt.com/ https://plundervolt.com/
  • Diggsey 6y ago
    It's not just temperature: many laptops also hit their power limits under full load. I had a Surface Book 2 that was particularly bad for this, I think because it uses the same connector as older versions, and it could not supply enough power. Undervolting seemed to help quite a bit.
    • macjohnmcc 6y ago
      MacBook Pros have this problem. You cannot achieve maximum performance without using both the external adapter and the internal battery. Not sure about the most recent models but true of mine (2013).
    • XMPPwocky 6y ago
      Annoyingly, there are 3 major related limits for Intel mobile CPUs- thermal, power (both an instantaneous, absolute max limit and a set of "okay you can use 25W for up to 5 seconds but then have to stop" limits), and current. Within that envelope, the CPU can boost up to its max turbo frequency when needed.
• bserge 6y ago
  Of course it does. Undervolting is simply finding the lowest voltage your unit can stably work at. The only result of undervolting on modern CPUs is lower temperature; performance actually goes up as the processor still aims to hit its set TDP/TPL limits. Lower voltage = higher clocks for longer on all Intel CPUs that can be undervolted. I believe it's the same for new AMDs, but I haven't had the chance to test one. You're basically fine tuning your pet rock - some silicon is higher quality and can do better than the stock voltages that were set for thousands/millions of units out of the factory.
• ezoe 6y ago
  Many computers, especially those fan less laptop/2-in-1 tablet, doesn't have adequate cooling system. If CPU was used too much, it instantly reach the temperature threshold, then forced down clock and stall kicks in to save the CPU, repeat the cycle. Which way do you prefer? endless cycle of 60fps for 10 seconds followed by shuttering for 10 seconds, OR stable 20fps.
• swiley 6y ago
  IME on most portable computers it's heat dissipation that's giving you the upper bound on clock speed not the CPU's actual upper bound.
• xxs 6y ago
  of course it does - less voltage => more power headroom and less overall power, less heat dissipated => more thermal headroom. If the silicon doesn't need the voltage, more voltage is only harmful. I can run my skylake alike laptop at -170mV offset (which is borderline golden chip), stable at prime 95 and whatnot. Prime95 runs below 70C.
• BMSmnqXAE4yfe1 6y ago
  Voltage is an energy gap between on and off state of the transistor. There is also random noise on top of that gap. And that noise can sometimes cause the transistor to flip randomly, which results in an error. More voltage means system is more stable and has less random errors. But in gaming people often don't care if there is an error or two now and then, so they can tradeoff stability for lower power usage. Companies don't like that, because that means more technical support when programs randomly crash.
• ThePhysicist 6y ago
  It helps a bit to reduce power/thermal throttling, from my experience the effect is not very strong though (maybe 5-10 % at most I'd say). If your CPU gets thermally throttled a lot it's more likely that you have a faulty or underdimensioned heat sink, in that case I'd try to apply better thermal paste and/or ensure the heat sink properly connects to the CPU. My Alienware throttled the CPU a lot due to overheating because they didn't apply the thermal compound right during fabrication (and seemed to use cheap compound with low conductivity), applying better thermal compound fixed that problem reliably, while undervolting the CPU did almost nothing in that case.
• necheffa 6y ago
  A lot of laptops are built with pretty lack luster thermal design. Less voltage means less waste heat. If you can lower voltage without lowering clock speed, you'll be able to maintain turbo boost longer instead of constantly thermal throttling. Not my first recommendation but it is a valid strategy.