CPU CPU Undervolting, How much did you achieve?

[BryceK]

Hi All,

Currently I'm busy with undervolting my I7-8700. Since yesterday i'm at -0,14v and got some nice temp drop without any lose of preformance.

I'm using a Intel Core I7-8700 with a Noctua NH-L9I and Thermal grizzly kryonaut as paste.


my default values are as following:

Max Temp of 72 degrees Celsius
0,994v (according to Bios)
3,81 Ghz core speed (no boost)

Values at -0,14 are as following:

Max Temp of 61 degrees Celsius
0,854v (according to Bios)
3,81 Ghz core speed (no boost)

That is already a nice drop of 11 degrees. I'm going to continue and test untill I hit that BSOD. But what are your experiences with undervolting and your results?

 

[jtd871]

Which motherboard are you using?

 

[rcodi]

I'm certainly going to do further testing but I just dropped my offset to -0.15 and the results are pretty dramatic showing an 11c drop just like yours. I adjusted Intelburntest to High instead of Standard because it was clearing the test too quickly to get an accurate temperature. No drop in performance, only temperature and total package wattage.

Setup:
Delidded i5 8400 with Conductonaut
L9i with NT-H1
Asus Z370-I

Here's an imgur album of stock and undervolted results.

Edit: I dropped it further to .18, disabled MCE, kept performance mode on. Seems to be stable here so far so I'll see how it is long term with real world workloads. I ran it at .20 and it might be too much for my chip because I had some freezes during the burn test even though it completed with the same performance. I suspect I'll see further improvement when my tube of Kryonaut arrives and I reseat the heatsink with it plus remove the VRM sink that's impeding airflow on the side of the l9i.

 

[BryceK]

Which motherboard are you using?

I got a Asus Z370-I

@RushNY I also have to turn my heatsink arround, but also have to remove the other sink. Since it will improve airlow, I quess it will drop temps even more.

 

[BryceK]

Update:

at -0,19 I got my BSOD. Making -0,18 the last fully completed stress test.

Values at -0,18 are as following:

Max Temp of 57 degrees Celsius
0,814v (according to Bios)
3,81 Ghz core speed (no boost)

Tomorrow I will turn my heatsink around, for now I'm gonna do a long test on -0,18v

 

[BryceK]

Ran some tests overnight (12 hour load) in XTU. -0,18v gave a BSOD after an hour of testing and -0,17v aswell but after 6 hours. Current on -0,16v and holding

Also did reseat the heatsink, but didn't gave temp improvements on the CPU, on the RAM it did =D

 

[rcodi]

Ran some tests overnight (12 hour load) in XTU. -0,18v gave a BSOD after an hour of testing and -0,17v aswell but after 6 hours. Current on -0,16v and holding

Also did reseat the heatsink, but didn't gave temp improvements on the CPU, on the RAM it did =D

Glad you mentioned XTU I was wondering why my temps were so much higher. Seems like XTU stress test simulates real world usage instead of synthetic like Intel Burn Test. My temps under XTU stress test matched yours at 57C. Very happy at .18 right now but I may try .19 shortly just to see if it's stable.

Did you pull off the VRM sinks? My Kryonaut tube won't be here until Tuesday so I'm waiting until then to remove mine and check cooler orientation.

 

[owliwar]

I'm not close to my PC till next week but I managed -0.115v offset on a cheap matx motherboard. I'm using an i7 4790 and temps dropbed by 10c to 12c with my havik 140 cooler. When I downsized to low profile cooler I couldn't keep the same Undervolt
As temps were reaching 90c

Now its around -0.085v stable

 

[BryceK]

@RushNY, I did remove the VRM heatsink.

Probably have to retest something, noticed that even at -0,16v that the CPU would get some weird BSODs in normale usage.

Making my win10 not workable at all, took me 4 hours to do a reinstall since the undervolting also adjusted some bios settings which didnt reconize the boot usb.

Might go and test on -0,15v. Did you do anything in the bios, which helped?

 

[rcodi]

@RushNY, I did remove the VRM heatsink.

Probably have to retest something, noticed that even at -0,16v that the CPU would get some weird BSODs in normale usage.

Making my win10 not workable at all, took me 4 hours to do a reinstall since the undervolting also adjusted some bios settings which didnt reconize the boot usb.

Might go and test on -0,15v. Did you do anything in the bios, which helped?

I have multicore enhancement disabled and performance mode enabled, haven't touched anything else.

 

[zovc]

I don't remember the specifics, but I had a 4790K in a Mini-Box M350 with a NH-L9i cooling it. I undervolted and underclocked the CPU, but actually overclocked (and increased the voltage) of the iGPU and was able to run Resident Evil 5 playable at I think 720p.

It wasn't a great situation for that application, but I think doing this sort of thing with the upcoming Ryzen APUs could be pretty interesting!

 

[rcodi]

I don't remember the specifics, but I had a 4790K in a Mini-Box M350 with a NH-L9i cooling it. I undervolted and underclocked the CPU, but actually overclocked (and increased the voltage) of the iGPU and was able to run Resident Evil 5 playable at I think 720p.

It wasn't a great situation for that application, but I think doing this sort of thing with the upcoming Ryzen APUs could be pretty interesting!

Totally, I'm hoping the top models (Intel or Ryzen variant) will be close enough to the 570 for me to ditch the card and run just the processor under an AIO.

 

[marcosopeth]

Hi All,

Currently I'm busy with undervolting my I7-8700. Since yesterday i'm at -0,14v and got some nice temp drop without any lose of preformance.

I'm using a Intel Core I7-8700 with a Noctua NH-L9I and Thermal grizzly kryonaut as paste.


my default values are as following:

Max Temp of 72 degrees Celsius
0,994v (according to Bios)
3,81 Ghz core speed (no boost)

Values at -0,14 are as following:

Max Temp of 61 degrees Celsius
0,854v (according to Bios)
3,81 Ghz core speed (no boost)

That is already a nice drop of 11 degrees. I'm going to continue and test untill I hit that BSOD. But what are your experiences with undervolting and your results?

hey bro, whats is the TDP of the i7 8700 under stress? Before and After Undervolt? Thanks!

 

[XcPNehVYlE4A3C]

dropped 0.1 something on skull canyon NUC for 5-10 degrees temp drop using XTU. helped fan noise.

some results from undervolting a deskmini here too:

ASRock’s Z370 DeskMini GTX1060 – Barebones Bonanza? (Part 2) – SFF.Network

smallformfactor.net

 

[Valantar]

hey bro, whats is the TDP of the i7 8700 under stress? Before and After Undervolt? Thanks!

Do you mean power draw? TDP is a specification, it doesn't change just because you change some settings. Also, TDP is not directly equal to power draw or heat output in modern CPUs.