New Microcode of Skylake X 50654 fixing AVX2/AVX512 performance penalty is coming soon.

[restsugavan]

According to Intel 02007006 microcode DATE 2023-03-06 for Skylake X SKUs ( CPUID 50654 ) patched on R6E 3801 Official BIOS. The microcode above prevented " DOWNFALL " vulnerable issue attack on " GATHER " instruction of Skylake X Series CPU. ( aka Core i9 78XX-7980XE ).

Even it prevented " DOWNFALL " vulnerable issue efficiently but on other hand it cause side effect of Skylake X CPU performance. Specially FPU units those microcode slow down FMA3/AVX2/AVX512 performance penalty 30-50%. 

Now Intel's engineer had been complete working on these issue.

The new microcode was publish on 2023-07-28. To bring back Skylake X FPU performace. 😁 

[Int8bldr]

Thank you! Very much appreciated!

[PanosXidis24]

what diffrences?

[tistou77]

Tested the new microcode, same performance as with the old one on the cpu-z bench (and for the SSD benchmarks)

[Int8bldr]

I think the new uCode is mainly related to the AVX 512 gather / scatter machine instructions performance degradation which took a serious hit with the "DOWNFALL" security issue fix in previous uCode. I think the new uCode are supposed to fix the performance problem. If you are not using s/w that take advantage of AVX 512 gather / scatter instructions, then you will likely not see much of a change... 
AVX 512 gather scatter are specifically these machine AVX-512 F / VL instructions: 

- VGATHERDPS,  VGATHERDPD, VGATHERQPS, VGATHERQPD

- VSCATTERDPS, VSCATTERDPD, VSCATTERQPS, VSCATTERQPD 

-VSCATTERPF0DPS, VSCATTERPF0QPS, VSCATTERPF0DPD, VSCATTERPF0QPD and 

-VSCATTERPF1DPS, VSCATTERPF1QPS, VSCATTERPF1DPD, VSCATTERPF1QPD

if you're interested. very powerful when reading and storing spares matrices (or vectors). So you avoid reding and writing the 0.0f values in a matrix/vector for instance, saving memory bandwidth. Well, at least in theory until security issues like "DOWNFALL" comes along 🤣.

[PanosXidis24]

@Int8bldr im using latest Bios 3801 on rampage with modding CPU MICROCODE the older one on 10XXX series

5000010!

[PanosXidis24]

@tistou77  mod your bios with this cpu microcode https://file.io/QDYRPnRWBfFI is the oldest one and report back here your perfomance!!! make sure on system32 delete mcuintel.dll

[tistou77]

At the time I had already tested the different microcodes, no real differences, but I disabled the Meltdown and Spectre patch in the registry
And the performances are roughly the same as today with new microcode

[Int8bldr]

i agree with you. with the latest uCode a lot of performance degradation that has occurred due to all the security fixes in teh uCodes the last years are now fixed so the CPU is back to original performance more or less.

make sense:

- first the priority for Intel was to patch the uCode to fix the security issue and performance was secondary.

- now several years later they have gone back and put more time into the later uCodes making the security fixes perform as well.

I'm happy intel took the time to do this work. Knowing they will eventually take care of the CPU value - performance and security, it makes me more confident buying next gen intel HEDT.

I'm having my eye on the Granite Rapids gen which looks to be truly impressive, coming out this year. Hope there will be a reasonably affordable core i9 style HEDT version of the Granite Rapids Xeon. that's a candidate to upgrade to...

[Cherry_PL_]

You can also disable it by this easy tool - https://www.grc.com/inspectre.htm 

I didn't test it on x299, but back in the days when i disabled it on x79 and i7 3960x , FPS in some games boosted really crazy. 

[tistou77]

Yes, it’s true that it’s been a few years since there was anything new on the HEDT side
Asus must be eager to produce and sell the Rampage VII Extreme 😁