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Not to mention that with the latest few generations of CPUs Intel has also increased burst/decreased base clock while promising unrealistic power draws. In oth

by mtgx 6y ago

Not to mention that with the latest few generations of CPUs Intel has also increased burst/decreased base clock while promising unrealistic power draws. In other words, Intel's CPUs are mostly about "burst" performance these days, too. They don't get anywhere the promised peak performance for any significant amount of time. https://www.anandtech.com/show/13544/why-intel-processors-draw-more-power-than-expected-tdp-turbo https://www.anandtech.com/show/13544/why-intel-processors-dr...

paulmd 6y ago
Oh boy, here comes the AMD peanut gallery. The conclusion of your article is precisely about how motherboard manufacturers don't obey the official/nominal behavior and how that makes it irrelevant: > Any modern BIOS system, particularly from the major motherboard vendors, will have options to set power limits (long power limit, short power limit) and power duration. In most cases, at default settings, the user won’t know what these are set to because it will just say ‘Auto’, which is a codeword for ‘we know what we want to set it as, don’t worry about it’. The vendors will have the values stored in memory and use them, but all the user will see is ‘Auto’. This lets them set PL2 to 4096W and Tau to something very large, such as 65535, or -1 (infinity, depending on the BIOS setup). This means the CPU will run in its turbo modes all day and all week, just as long as it doesn’t hit thermal limits. Intel desktop processors will sustain boosts for an arbitrary amount of time. Yes, they will exceed the nominal TDP while doing so, so do AMD processors (AMD's version of "PL2", which they call the "PPT limit", allows power consumption up to 30% higher than the nominal TDP while boosting, and there is no official limit to how long this state may occur). These limits are of course observed much more strictly on laptops since power/thermal constraints actually make a real-world difference there. But overall, Ice Lake perf/watt is competitive with Renoir and its IPC and per-core performance is actually higher than Renoir. You just get fewer cores.

by mtgx 6y ago

paulmd 6y ago

Oh boy, here comes the AMD peanut gallery. The conclusion of your article is precisely about how motherboard manufacturers don't obey the official/nominal behavior and how that makes it irrelevant: > Any modern BIOS system, particularly from the major motherboard vendors, will have options to set power limits (long power limit, short power limit) and power duration. In most cases, at default settings, the user won’t know what these are set to because it will just say ‘Auto’, which is a codeword for ‘we know what we want to set it as, don’t worry about it’. The vendors will have the values stored in memory and use them, but all the user will see is ‘Auto’. This lets them set PL2 to 4096W and Tau to something very large, such as 65535, or -1 (infinity, depending on the BIOS setup). This means the CPU will run in its turbo modes all day and all week, just as long as it doesn’t hit thermal limits. Intel desktop processors will sustain boosts for an arbitrary amount of time. Yes, they will exceed the nominal TDP while doing so, so do AMD processors (AMD's version of "PL2", which they call the "PPT limit", allows power consumption up to 30% higher than the nominal TDP while boosting, and there is no official limit to how long this state may occur). These limits are of course observed much more strictly on laptops since power/thermal constraints actually make a real-world difference there. But overall, Ice Lake perf/watt is competitive with Renoir and its IPC and per-core performance is actually higher than Renoir. You just get fewer cores.