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Confused about CPU voltage....

Omaran
Level 7
Hi all! Not OC'd for a long time (not since OC'ing the original i7 920).

I now have an i5 8600K, ASUS ROG STRIX Z370-F, Corsair Vengeance LPX 16GB DDR4-3000MhZ and a Corsair H100i v2 AIO.

I originally OC'd the i5 to 5GhZ, temps were good but I got a couple of BSOD while gaming, so loaded defaults and started again - I had read so many forum posts and changed so many settings I got confused what I had done so started afresh.

I'm currently running at 4.8GhZ, this is stable, temps are low and I'm quite happy with it really, but it would be nice to hit 5GhZ stable.

I have currently set:

XMP - on
SVID - best case scenario
Sync all cores
Core ratio limit - 48
CPU core/cache voltage - manual
CPU core voltage override - 1.300
Power saving and performance mode - performance mode
LLC -5
Speedstep I have left on, I don't want it running at OC levels all the time

I use Prime95, CPU-Z, Coretemp and the Corsair Link Utilty to monitor my OC.

Max temps with this OC are 67, core voltage 1.280.

Now I try 4.9GhZ, I change the Core ratio limit to 49 and leave all the other settings as above.

Running Prime95 blend test, temps are stil good, core voltage is at 1.280 but after about 10 minutes one or two cores drop out. So I up the CPU core voltage override in increments and try again a few times with the same results - but what confuses me is the voltage in CPU-Z and Corsair Link still show around 1.280, even when I get the CPU core voltage in the BIOS up to 1.350? :confused:

I tried adaptive voltage and entered the turbo override as 1.350, thinking this would cap it at 1.35 - it then hit 1.470 in CPU-Z (that test didn't run long, I stopped it straight away!)

Any advice? With the temps I'm getting I'm sure I can get to 5GhZ but I just can't figure out the voltage with this 😕

I've run at 4.8GhZ for a month or so on BIOS 0614, I had LLC set to 4 then, with it set to 5 I had cores drop out, with it set to 6 my PC went through POST but wouldn't boot to Windows - in fact it went through the ASUS repair utilty and just hung doing that, I thought I had bricked it but fortunately I managed to get back in the BIOS and load defaults :eek: I updated the BIOS to 0616 this morning and had to redo my OC, it doesn't seem to make much difference if I set LLC to 4 or 5 now, but I'm still scared to change it to 6 after my previous experience!! 😮

TIA!
8,362 Views
7 REPLIES 7

Alcasczar
Level 7
Is your CPU de-lidded?

You can use this below video as a guide, I found it very good for my OC but I don't like the temps even though they are fine. I went back to stock turbo 4.7GHZ cause the performance gain was not noticeable for the games I play

This video is based on the MAXIMUS HERO X .
https://www.youtube.com/watch?v=CoUtA7DKXhU

Nate152
Moderator
Hi Omaran

In the bios - CPU Power Management set:

IA AC Load Line - .01
IA DC Load Line - .01

DIGI+
LLC Level 6

This should keep the voltage at or close to what you set, with LLC at Level 6 it may overshoot 0.012v.

Thanks guys 🙂

No, not delidded.

I set:

IA AC Load Line - .01
IA DC Load Line - .01

Also messed about with adaptive voltage again. At 1.35 and 5GhZ I get decent temps but one or two cores drop out when running Prime95 blend test after 10-15 minutes.

I know it runs stable at 4.8GhZ so now have set adaptive at 1.34 (Coretemp shows just below 1.35, CPU-Z around 1.32) and have the AVX offset to 2. I know this means Prime95 will run at 4.8GhZ (but I know that's stable) and have been playing PUBG for a few hours with it at 5GhZ. I think I'll be happy with that 🙂 I might try to get my vcore down a bit though

Nate152 wrote:
Hi Omaran

In the bios - CPU Power Management set:

IA AC Load Line - .01
IA DC Load Line - .01

DIGI+
LLC Level 6

This should keep the voltage at or close to what you set, with LLC at Level 6 it may overshoot 0.012v.


Hi Nate, sorry for the delay in replying, I've not been on my PC for a couple of days.

I actually had LLC 5 - LLC 6 does actually set the voltage about right.

I tried Prime95 again with AVX test disabled and at 5GhZ I still see a core drop out after around 10 minutes, even pushed up to 1.36v with temps around the low 70's. I've read conflicting reports on what is a safe voltage for the i5 8600K so I don't want to push it up much more : /

I think I'll go back to my previous settings and use gaming as the real test (as that's about all I use my PC for), this overclocking lark can get a bit addictive searching for that stable 5GhZ which probably doesn't make much difference to gaming!

One thing I was wondering though - for SVID support it recommends disabling it if overclocking, but most posts I see say to enable it - what's the difference between 'enabled' and 'auto'? I currently have mine set to auto

Nate152
Moderator
That's looking better,

You can go back to LLC Level 5 and see if this puts the voltage right at 1.34v, you may then need to up it to 1.35v.

Does setting LLC back to Level 5 get the voltage right at 1.34v ?

Wiwells
Level 7
Right there with you Omaran... Seems like my system runs best @ 4.9Ghz 1.28v LLC5 (no cores drop out in xtu but my realbench scores stink?) I've tried upping the vcore and cores drop out. In HWbot, everyone that gets killer scores is running like 1.5+ vcore (I get into the 90*s just in startup with anything above 1.45) but they're running maximus boards, I get no benefits by raising the vcore. I have to be missing something. And why do the built in auto tweaks bump the fsb but none of the guides I've read even mention tweaking the fsb.

phoenixx74
Level 7
bF code, vcore at 0.71 volts using intel core i7 7700 4.20 GHz will raising the voltage help with the code, also what should I set it at if so?