CPU Advice on undervolting CPU and GPU

[SFF Scrub]

Any advice I could get on undervoting a cpu / gpu combo would be appreciated

 

[Smanci]

Put the voltage smaller until computer doesn't work. I think that's it in a nutshell.

 

[blubblob]

For the CPU I would start by dropping the voltage in 50mV steps. Then run some CPU stress tests to see if it's still stable.
Just like with overclocking it's important to not only test the full load but especially the load change scenarios, as there will be a dip in voltage on the change from low to high loads.
You'll likely hit a spot that is mostly stable but crashes irregularly in some applications with sudden shifts in loads (Adobe Premiere and Keyshot does it for me.) Add back 50mV and you should be good to go.

I'm personally running a 6700k @4.3Ghz and -200mV offset - which results in 1.15v at full load. The thermal gains are (subjectively) considerable.

For the GPU it's a little more complex depending on whether you are using a Nvidia or AMD card. AMD cards reportedly respond very well to undervolting, for Nvidia cards it's a little fiddly to get to work, but it can be done with the V/F Curve Editor (i believe there still isn't a button for it, you have to use CTRL+F) in Afterburner. If maximum power draw is your concern it might be enough to just set the power limit appropriately - even though you'll be losing a bit of performance.

 

[SFF Scrub]

I'm personally running a 6700k @4.3Ghz and -200mV offset - which results in 1.15v at full load. The thermal gains are (subjectively) considerable.

So I haven't bought any parts yet although that is the next step. I was looking at the i7 7700 or the 7700T (The T has a 35W draw rather than the regular 65W). The T also gives a 2.9GHz clock speed as opposed to 3.6GHz. In your opinion does it make more sense to get the 7700 and undervolt or get the 7700T and keep stock specs?

 

[Phuncz]

The comparison between the i7-7700 and T-version have been asked a few times before, a lot of info in these these topics:
https://smallformfactor.net/forum/threads/q-i7-7700t-or-i7-7700.2144/
https://smallformfactor.net/forum/threads/low-power-draw-cpu-thread.2030/

 

[SFF Scrub]

The comparison between the i7-7700 and T-version have been asked a few times before, a lot of info in these these topics:
https://smallformfactor.net/forum/threads/q-i7-7700t-or-i7-7700.2144/
https://smallformfactor.net/forum/threads/low-power-draw-cpu-thread.2030/

Thanks for the info

 

[eutholevonik]

Will it let you underclock a i7 7700 non-K SKU?

I have my i7 4790k underclock at 4ghz at .95 volts. Probably can go lower but haven't got to test any farther.

 

[blubblob]

You won't be able to underCLOCK a non-K CPU (at least the recent models). UnderVOLTING is usually entirely dependent on the mainboard though.

 

[eutholevonik]

Yeah, I meant undervolting

 

[SFF Scrub]

I meant the k version, although I think I'm gonna go with the T model

 

[zovc]

You won't be able to underCLOCK a non-K CPU (at least the recent models). UnderVOLTING is usually entirely dependent on the mainboard though.

In my experience, you can underclock CPUs that are non-K series. I have, in the pursuit of undervolting (U-series) laptops to improve battery life, lowered clock speeds to keep them stable.

 

[aquelito]

You won't be able to underCLOCK a non-K CPU (at least the recent models). UnderVOLTING is usually entirely dependent on the mainboard though.

Some people can modifiy your BIOS to overclock non-K CPU, on Z170 chipset only though.