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6850k core clock wierdness

elkido122

Senior member
Jan 10, 2015
275
2
81
i am using afterburner to show all my cores clocks on all cores. i noticed in some multi core games that i play all cores are only boosting to a max or 3699 mhz and not 3800mhz. i also noticed that some of those cores fluctuate and run at 3499 instead of 3699 sometimes not all the time. what could be causing this kind of weirdness to happen. i went through my windows power settings all seem fine. any help to make all cores run up to the 3800 would be appreciated. thanks.

specs are as followed.
6850k i7
asus x99 pro usb 3.1 motherboard
corsair ddr4 2400 running xmp at 16-16-16-39 1.2volts
gtx1080ti sc black edition
960 evo 500gb

thanks guys
 

Timmah!

Senior member
Jul 24, 2010
761
65
91
6850K boosts all cores only to 3,7GHz. When you see 3,8GHz on occasion, thats in situation, where only single core (or possibly too) is taxed. If you turn on TurboBoost 3.0, this can actually change to 4GHz.

Regarding the clock fluctuating, its very likely when the load is not constant, so the cores clock up and down as they need - its actually happening all the time with the regular power saving features switched on. The clock is only keeping at its max value, when the cores are loaded continually, like when you run Cinebench or some other benchmark.

So everything works as it should IMO.

If you want your cores to run at constant high clock, you need to turn off power saving features in BIOS - or maybe just run Windows in High Performance mode - not sure about that.
 

elkido122

Senior member
Jan 10, 2015
275
2
81
i just didnt think it would change so much in a cpu demanding game. i remember on my old msi x99 gaming pro carbon board it was pinned at 3.8 in games at all times on all cores... i dont know weird i guess.
 

elkido122

Senior member
Jan 10, 2015
275
2
81
So are you guys saying the behavior I'm seeing is normal? I did an encode on handbrake and all cores only ran at 3.5 GHz... Kinda was weird
 

Timmah!

Senior member
Jul 24, 2010
761
65
91
Try Cinebench. If its clocked at 3,7GHz throughout the entire run and your score around 1150 points, it should be OK, as i told you.
 

elkido122

Senior member
Jan 10, 2015
275
2
81
timmah, i got 1157 on cinebench with all cores at 3.7. now why does Handbrake run 6 cores only at 3.5 when encoding? thats below the base clock.. weird
 

Dufus

Senior member
Sep 20, 2010
675
119
101
What's your AVX offset to?

Handbrake uses AVX, Cinebench doesn't.
 

pjmssn

Member
Aug 17, 2017
89
11
71
I too had similar behavior with Handbrake on my dual Xeon system while cinebench is able to load all the CPUs at 100%.
 

Dufus

Senior member
Sep 20, 2010
675
119
101
Check your BIOS settings for something like "AVX2 Negative Offset" although technically it is a ratio limit rather than an offset.

If you can run with it set to zero while keeping within thermal and power, your own requirements or spec, then that's fine. It's more of use when running the limits at the AVX2 ratio might allow higher clocks at the near same voltage for non-AVX2 operation or due to power / thermal constraints. There is still not so much software that takes advantage of AVX2 which has been around for something like 4 years now.

Also check turbo boost max 3.0. If enabled it can allow some cores to run at higher ratio's. Check out some Broadwell-E OC'ing guides for further info.

Also check Vsa, if left in auto can be very high on some boards when using higher DRAM clocks (XMP). Usually best not to use auto when possible but one must have an idea what is needed.
 
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