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Need some help with this undervolting i7 8700 non-k

happyfatgamerzz
Level 7
Hi All,

Using a Maximus X hero motherboard with a non-delidded i7 8700 non-k cpu

I am having some weird issues with this undervolting. I am undervolting due to high ambient temps in the area I live in and using a mid-range air cooler (cyorig quad lumi). When I use offset voltage of -0.200 (which has a higher cpu vcore of 1.072 volts on load) than when I set a manual setting of 1.04 vcore. The offset mode is more unstable than the manual voltage. The only difference is that in the offset mode the LLC is set to auto while the manual voltage I am using LLC of value 6, in addition that cpu svid is disabled on manual vcore and the VCCIO/VCCSA are lower than on offset mode.

How can a lowered manual voltage with forced LLC of 6 be more stable than the offset mode (which has a higher vcore)?? I have done so far a 16 hour run of prime 95 avx , rogbench and IMC of 1500% with the manual settings and have passed, while the offset mode just fails after a short time. In BFV the offset mode is also unstable while the manual vcore mode is stable as a rock.

TLDR, offset mode higher vcore voltages but unstable, manual mode lower vcore but stable.

Using Hwinfo 64 to monitor.

Disabled MCE and lowered down the XMP auto voltages
core clocks: 4300 mhz (all 6 cores) forced all to be 4300 mhz in bios for both offset and manual.
Ambient temps: 33 degree C
CPU temps in prime 95 avx on 29.4 - 81 degree C
CPU temps in gaming - 50 degree C
CPU cooler: Cryorig quad lumi
RAM: 16 gigs of cosair 3200 ram
Vcore: 1.04 volts (on load with LLC 6 it becomes 1.056volts)
VCCIO / VCCSA: 1.1 volts ~ 1.12 or 1.13 volts in HWinfo 64 (offset mode the VCCIO/VCCSA was 1.35v and 1.15v respectively).
LLC : 6 (on manual, auto on using offset mode).
CPU VID support: (disabled on manual, auto on using offset mode).
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6 REPLIES 6

happyfatgamerzz
Level 7
Hmmm i should not use Rise of the Tomb raider, seems to have issues with the current 4XX drivers with that game, alt-tabbing causes a reproducible bluescreen.

happyfatgamerzz wrote:
Hmmm i should not use Rise of the Tomb raider, seems to have issues with the current 4XX drivers with that game, alt-tabbing causes a reproducible bluescreen.


So you used XMP in one but not the other? I noticed that XMP greatly increased the vccio vccsa voltage's on my board. (Either that or it was the auto settings)

Guitarmageddon888 wrote:
So you used XMP in one but not the other? I noticed that XMP greatly increased the vccio vccsa voltage's on my board. (Either that or it was the auto settings)


Sorry they both have XMP , except the offset one has it set on auto with the insane vccio voltages.

JustinThyme
Level 13
33C ambient?! Holy Cow! Sell PC and invest in AC!!
Unfortunately electrons and heat don’t play well even if you slow it down. By the time you under volt enough to make up for that ambient you might get it to boot and play minesweeper but it’s going to crash and burn on power point.*

I don’t know how you guys do It. I can take that kinda heat for awhile but can’t sit in it non stop. I can’t sleep in anything above 22C. My WC loop max temp alarms at 32C and your ambient is 33C OMG! Hottest I’ve ever seen was Aswan Egypt in the summer where it was hitting 45C+ every day. When I first got there I thought it was abandoned. No one in sight and the AC on the mini bus could not keep up. Went out later and after dark it exploded with people everywhere because at night the temps were dropping dramatically.**

If I had no choice in that environment and it had to be that hot I’d invest in a peltier. **



“Two things are infinite: the universe and human stupidity, I'm not sure about the former” ~ Albert Einstein

JustinThyme wrote:
33C ambient?! Holy Cow! Sell PC and invest in AC!!
Unfortunately electrons and heat don’t play well even if you slow it down. By the time you under volt enough to make up for that ambient you might get it to boot and play minesweeper but it’s going to crash and burn on power point.*

I don’t know how you guys do It. I can take that kinda heat for awhile but can’t sit in it non stop. I can’t sleep in anything above 22C. My WC loop max temp alarms at 32C and your ambient is 33C OMG! Hottest I’ve ever seen was Aswan Egypt in the summer where it was hitting 45C+ every day. When I first got there I thought it was abandoned. No one in sight and the AC on the mini bus could not keep up. Went out later and after dark it exploded with people everywhere because at night the temps were dropping dramatically.**

If I had no choice in that environment and it had to be that hot I’d invest in a peltier. **


I tried the pelter technology about 20 years back but the issue is when you cool boot it up, there would be condensation on the pelter side and if you are not careful the water will drip into the cpu socket. Luckily the ABIT mother board and celeron 300 survived lol.

But coming back to the thread how come the offset seems voltage seems to be more unstable than the manually set voltages (which are lowered).
Does the LLC setting to 6 makes that much of a difference? Also the SVID CPU support wouldnt make much of a difference yes?

Hmm maybe another question would be what is the auto voltage setting for the maximus x hero ? I still can't find a correlation why the manual input of the LLC makes the machine stable when the overall (core and vccio) voltages of it are lowered.