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5.0Ghz questions

Darkness1015
Level 7
i7-8700K @ 5Ghz, everything is stable. In the BIOS I started with manual mode and the vcore is set to 1.270.

AVX Offset = -2
CPU SVID = auto
SVID Behavior: Best Case Scenario
LLC = Level 6


1. In HWInfo64 and CPU-Z I see the vcore with no load at 1.260. Is it normal to see a +/- of 0.01 ? I know by setting "SVID Behavior: Best Case Scenario" it changes the IA AC/DC LL = 0.01, is this what is showing or something else ?

2. When running load, I see the CPU frequency at 5Ghz, but it does fluctuate down to 4.7Ghz and back up to 5Ghz. Is this normal or am I missing something ? I do have SpeedStep/etc enabled, and Windows Balanced power mode, so I expect to see down fluctuations when idle, but wasnt sure if it still should show some fluctuation under load.
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3 REPLIES 3

jab383
Level 13
Those OC settings look good. The real test of how well an OC profile is working is stability. If it doesn't crash in the applications you use, it's good.

Variance of +/- .01 is quite normal. The VRMs and the sensors are not highly precise - just good enough to tell if things are working.

Frequency fluctuation like that under load is often the AVX setback coming into play when AVX instructions are encountered in the program. AVX offset is listed as -2 above, but the fluctuation is .3 GHz. Perhaps the offset in BIOS got back to -3. The other possible cause is throttling. When CPU temperature or power reaches an internal limit, the CPU slows down to protect itself. You can check for this with a temperature monitoring utility, eg. HWMONITOR.

Thanks for #1, good to know.

For #2, I see this with Prime95 (v26.6 no-AVX), Cinebench, Gaming, etc. So I dont think its AVX related. I also see it the same in HWInfo and CPU-Z. It does reach 5.0Ghz but then fluctuates between 4.7-5.0. I assume since the load being generated is 100% per core that it would be pinned at 5.0Ghz and not fluctuate. SpeedStep/EIST kick in for small periods even on 100% load ?

TheInfidel
Level 7
early batch of that cpu reaches 5.0 ghz with zero brain effort by simply auto ocing it. Tricky is 5.1+.
Watercooling , no temp issues ever, since this cpu stays dirt cold even on max load its like 60C which is nothing.
Do not use BALANCED mode for testing your max speed. Use High or ULTIMATE setting.