Haswell-E impossible to get it prime95 stable with a reasonable OC?

[AaA91]

Hi Guys!

Those are my specs :-
i7 5820K @ 125x35 Core, 125x33 Cache
Asus X99-Pro/ USB 3.1
16 GB Corsair Veng. LPX DDR4-3000

I am trying to be prime95 28.7 stable with a reasonable OC and have a very high difficulty of achieving this.

First I tried 125x35 @ 1.240V and it crashed in smallFFTs in about 35mins.
Increased Vcore to 1.255 and it crashed just shy of 2 hours. I increased it to 1.270V and was able to pass 4.5 hours then I moved to largeFFts (1344k), then It froze in less than 35 mins. I thought it might be the RAM so I overvolted it to 1.4 instead of 1.35 and froze after about 1.5 hours, I tried loosen the timings a tad and it crashed after 1 hour. I am now thinking it is the cache that is responsible for the freezes so I increased it to 1.25V instead of 1.21V. And I will see if it passes without issues.
(Edit: bam actually it froze again at the time of writing this thread, lol, so probably it is not the cache but something else)

I am really tired of this, it is really giving me headaches. My system otherwise passed Realbench for 8 hours, Aida64, OCCT (Small Data and Large Data Sets). So I tried prime95 as a final test and it failed miserably at it.
What concerns me is any of those programs are not using any of the new instructions, and when programs showed up using them I will have instability issues just like prime95.

 

[AaA91]

Thanks for the replays guys. I managed to stabilize it, all this acting up is because the CPU is lacking some VCCIN

 

[AaA91]

Well done OP. What have you set VCCIN to out of interest? Still good with the memory at full speed?

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Thanks. I tested it for 4 hours and it was stable during the test with 95% of the memory loaded, the memory speed was at 3000 MHz.

Interesting results. What VCCIN are you using as it might help me work out why my 5820K isn't stable above 125x33 as well?

I set VCCIN to 1.930 in BIOS LLC8 and it can reach 1.952 sometimes during stress tests.

AAA91, why only 1344k fft's ? i run either blend and it will cycle through all ftts in about 24hrs or i use the largest 4096 ftt

From what I've heard 1344K/1792K FFts are the hardest for the Haswells. Even harder than 4096K.

 

[AaA91]

Thanks for the info. I'll check and see what my VCCIN is tonight. I take it LLC8 is the load-line calibration level? I'm using a Gigabyte board, so my LLC is described as normal, high, extreme etc.

Yeah LLC = Load-Line Calibration. According to BIOS description it runs at 100% level (There is one level higher that is Level 9 and it is @ 125%), so yours at high is probably equivalent to LLC 8 on my Asus mobo.

Good Luck