Originally Posted by Nighthog
I had trouble with AVX2 LargeFFT when going for 4866/1900... It became utterly finicky for voltages on the VDDG/VDDP & vSOC. Lower speeds are more tolerable with most voltages, but if set wrong "work" but can give glitches. Not high Frequency like this, doesn't tolerate "wrong" settings.
Only ~950/950 VDDG_CCD/IOD works to make it pass, having enough VDDP is also critical, the recommended 900mv is to little, even 1000mv wasn't really enough.
I might be suspecting the 3950X is more taxing on FCLK? Maybe AUTO doesn't work? I know they are high when on AUTO settings. Above 1000mv on VDDG voltages are finicky in general from my testing. They make AVX2 fail more often than not.
Low VDDG_CCD voltage will make AVX2 fail also. My sample has a floor around 950mv to function without fail.
I noted a weird crossloading issue, AVX2 would work if I did nothing major but the minute I started a YouTube video they would crash. Had to adjust the CAD_BUS settings to fix that.
The issue I saw was even weirder, which was the reasoning i decided to investigate CCD voltage.
Basically, running 3800/1900 @ 4400 mhz, was wondering if the high fclk was effecting the stability of core 6 after extended prime95 load.
The issue occurs on both blend, large ffts and small ffts and around a similar time mark (after 30 mins).
So I simply dropped to 3733/1866 leaving everything else as they were.
What happened stumped me, prime95 fails almost instantly on core 6 !
So this got me thinking that something get put "out of sync" be it voltages, frequencies or what not.
Boom! Again, worker 12 at 35 minutes, temperature does not seem to be the issue as it happens when ambients are lower or higher!
Something ive noted, worker 11 is processing
"FMA3 FFT length 72k, Pass1=384, Pass2=192, clm2"
while worker 12 is processing
"FMA3 FFT length 64k, Pass1=256, Pass2=256, clm2"
The crash looks like it occurs when the 12th worker is going to pass to the same FFT length as worker 11.
Really, we should take this conversation to its own thread
Apologies to the OP