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I saw on Steam a comment re AVX being required for the final boss fight (???) for [[Death Stranding]] on PC. Anyone know more about this? E.g. should it be included in the list, and if so for which version?
:No, it shouldn't. AVX has been available in the majority of processors for almost 10 years, I'd be shocked if everybody isn't enabling at least the base version of it which doesn't have any clock penalties, and Death Stranding's bare minimum processor requirement supports AVX. I have no idea why or what they were mentioning it for, aside from probably being mad that their 10 year old hardware didn't mess up on them until the last boss when the minimum was there for a reason. If it required AVX-512 (but doesn't list Skylake as a hard requirement) that would be a different matter but still one that belongs on the page for that game. --[[User:A Shortfall Of Gravitas|A Shortfall Of Gravitas]] ([[User talk:A Shortfall Of Gravitas|talk]]) 07:39, 18 July 2021 (UTC)
== Re: Downclocking ==
The percentages listed in that section aren't a reflection of how the processors actually handle things. A fixed ratio multiplier (multiplied by the processor bclk reference, so usually 100MHz unless somebody messed with it) is used to calculate the frequency drop, so any percentages are only relevant for whatever specific speed processor the person testing them tested on and at unmodified clock settings. See the link to the XTU guide I posted in that section. I'm not sure how to re-word it correctly because I don't feel like digging through somebody's findings for their specific model and figuring out the pre-set ratios it used, but for example on Broadwell-E the AVX2 drop ratio is 2x by default, which results in a drop of 200Mhz below the TB3 frequency, and it can be changed in either the BIOS or XTU given specific cooling and possibly slight core voltage increase if the processor is being overclocked to begin with. There is no curve built in of "more cores = lower speed" with AVX. the 5117 has the same 105W TDP but is clocked at 2.0 / 2.8 instead of 2.2 / 3.2 which is kind of suspicious.
Anyway, on an i7-6950x Broadwell-E with the AVX2 ratio set to the default of 2x, the processor TDP ignored because of sufficient water-cooling, and all cores set to a 4.2GHz turbo ratio, every core runs at 4.0GHz because there's no TDP to exceed. Even with TDP left on the defaults there's no real drop because the turbo max defaults to 185W and is heat-limited at that clock speed. Raising it even slightly would produce different results either from heat or exceeding max turbo TDP since voltages don't scale linearly with clock increase. Changing that ratio to 0x results in instability unless core voltages are raised, but since running all cores at 4.2GHz is much higher than the intended one core max turbo for that processor in the first place there's no real point in doing so. Likewise I suspect if I lowered my TDP to 105W via BIOS or XTU I'd immediately start seeing that kind of rapid tanking of performance with high all-core AVX2 usage regardless of whether the ratio offset was set or not. I'm too lazy to do it and original research is useless here anyway (unless you post it on stackexchange apparently), but that's just how the TDP and thermal limiting work on these things. It's a huge part of why everyone can sell these processors with massive turbo clocks and unlocked ratios and not worry about anyone frying them even though (mostly) nobody really understands what exactly it is they're changing or how any of it works. If they do, well, running your memory at the XMP speed it and the processor itself in the case of AMD was advertised at instead of its base frequency already voided the warranty on the processor so Intel / AMD don't really need to worry too much.
It doesn't have AVX512 so I can't test that but the behavior of both ratios is the same; a constant offset from the max ratio; This kind of test can't really be done on a "true" Xeon aside from some earlier v4 and possibly Skylake parts which could be forced to allow overclocking if their microcode wasn't updated, but Broadwell-E was a Xeon anyway and the same applies.
The defaults can be different between processors. On the linked Ice Lake, the information is almost certainly wrong in that the L1 downclock still exists but has the ratio set to 0x for that model and the L2 ratio is set to 1x. I suspect in XTU if someone was overclocking it they could adjust both ratios to be non-zero to keep voltages and thermals within a reasonable range while AVX code was running or set the L2 ratio to zero and increase allowed power / TDP a bit if they really needed the extra 100MHz of speed in AVX512 code.
AFAIK the whole notion of downclocking in the first place came about when the unlocked higher core count Haswell-Es were released and didn't implement this, and someone turned off both the thermal and power limits in their BIOS then tried to run heavy AVX2 code and fried their processor which now had everything telling it to turn off before it caught on fire disabled. Then they whined about it up and down the entire internet for 2 years, so Intel implemented the downclocking to avoid that in Broadwell-E and it became more necessary when power management changed with Skylake and TDP was followed less strictly anyway and AVX512 was even more of a power hog.
In any case my point is that if any hard numbers are to be left in that section they should probably be specified as examples, specific to those single processors, and in terms of base clock multipliers since percentages make little / no sense even on similar speed chips as seen from the 14C skylake server chip downclocking immensely to keep within the low TDP. --[[User:A Shortfall Of Gravitas|A Shortfall Of Gravitas]] ([[User talk:A Shortfall Of Gravitas|talk]]) 08:46, 18 July 2021 (UTC)
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