[SOLVED] 8700k stock speed , lower voltage = lower performance ?

[pmadeja]

Hello,

So I recently overclocked my 8700k to 4700mhz on all cores. It was my first time OCing. First stable voltage was 1.28. I tested it 2 times in RealBench for 1 hour and run some benchmarks,play games and it was stable. Temperatures in stress test were around 80C- 85C (sometimes spikes for 90+C but only for seconds, I watched entire time). In games temps doesn't go up more than 70C.

I decided to go back to stock settings anyway after that OC. Reseted mobo to default settings (AsRock z370 extreme4) and then I saw that in auto voltage mode mobo gives my cpu to much voltage (around 1.32v under stress test) so I thought if I OCed it and it works stable on 1.28v why should I use higher voltage.

Decided to change voltage manualy and set 1.15 first. PC got blue screen.
2nd try was 1.17 it passed stress test but HWInfo showed some cache error.
Then I changed for 1.2v and its super stable.

I think I can lower voltage more and set something between 1.17 and 1.2 but didnt have more time to run some tests.

Anyway my question is if lower voltages can affect cpu (lower cpu performance even if it passed tests ) ? I mean ... I thought auto settings should well personalized and then I saw this hight voltage mobo gives to my cpu and I'm confused now.

I know lower voltages = lower temps , but dont know if it affects performance somehow.

Sorry you had to read all this long story , I should just write this question

 

[ViktorHX]

It shouldn't make too much of a difference, but if you put it on too low voltage you may have stability problems, but no it shouldn't affect it, if you can you should go for it, lowering voltage will greatly improve your temps in some cases.

 

[TJ Hooker]

It shouldn't have any negative effect on performance, but why not just try it out? Run Cinebench a couple times at stock settings, a couple times with your undervolt, see if there's any (meaningful) difference.

 

[Karadjgne]

Lowering voltages doesn't lower performance. The cpu will always run at 100% of its ability, (ability and capacity are two totally different things) no matter what voltage is applied. But it will require voltages in a certain range, which is variable from cpu to cpu, even in the exact same family. Not enough voltage, and the cpu can't think straight, and you get bsod. Too much voltage and you cook the cores.

With that in mind, both Intel and Amd err on the side of caution. They don't test chips other than protypes for minimum voltages, they'll just set a high enough voltage to cover any discrepancy. This ends up usually in the 1.25-1.35v range.

OC is getting best speeds, at best voltages combined with best temps. So if leaving everything else stock, you can often down volt to find the minimum stable voltage your actual cpu needs to think straight. Conversely, many times a simple multiplier bump does not need any voltage change, since it's already higher than necessary.

IE: my old i5-3570k ran stock 1.25v. I could bump up the multiplier to 43 locked core and still be stable, but also down volted to 1.114v for minimum. End result was somewhat better performance (3.8GHz turbo vs 4.3GHz), better voltages (1.25v dropped to 1.114v) which netted a drop in load temps (83°C to 70°C) with Prime95 small fft.

That's quite common for a mild OC, with decent cooling, it's usually only high OC that will require voltage changes, current changes, LLC tweaks, Ring voltage changes, system agent adjustments etc.

 

[TJ Hooker]

There was any issue with recent AMD CPUs were if you set a fixed voltage (and left frequency on auto I believe), performance would drop as you reduced voltage even though the reported frequency wasn't affected. I think this was Ryzen 3000 chips only though. I definitely haven't heard of anything similar occurring with Intel, but it's easy enough to verify just in case.

 

[Karadjgne]

Sorta. The Ryzens are extremely responsive to PBO settings, they really don't breach the caps at all, so setting a fixed voltage will allow the Ryzen to max out amperages once it reaches its voltage cap, which has a byproduct of driving the VRM's harder/hotter than warranted. Forcing reduced clock speeds on certain cores that aren't under heavy usage. Done on a lower grade board, or an MSI midgrade x570 with a high core cpu like 3700x that gets problematic in a hurry.