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Kepler undervolting works!

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boxleitnerb

Platinum Member
Please forgive me if this is not news, but up to now I was under the impression that undervolting is not possible with Kepler since there is no voltage control. Well, I was dead wrong and it is totally easy.

Think of it as GPU boost reversed. Increasing the GPU clock offset will lead to lower voltages for each operating point (except idle). The trick is to keep the boost from actually overclocking the card above the maximum stock frequency.

For example with one of my Titans I get 1006 MHz at 1.1625V at stock settings. With +104 GPU clock but 80% power target, I get 1006 MHz at 1.0625V. Clocks stay the same, performance stays the same, but the card is cooler, therefore quieter and power consumption is reduced. In this case by about 40W (in Unigine Heaven).

Just thought I would share this with you 🙂
 
Do you get any stuttering? When AMD cards reach their power limit they rapidly switch back and forth between (450mhz?) and full speed.
 
Yuriman said:
Do you get any stuttering? When AMD cards reach their power limit they rapidly switch back and forth between (450mhz?) and full speed.
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Are you saying that you can't under volt AMD cards without stuttering? I'm not sure what you are talking about when you refer to "reach their power limit"?




@boxleitnerb, All cards have voltage control. Not all of the controllers used can be software controlled, though. If you under volt yours, I'd be curious to see if it effects the reported throttling while gaming some have reported. It might actually stop it if it keeps Titan off of the 265W limiter.
 
AMD cards have their own independent voltage control, but if you lower the "power limit" and exceed that limit you get stuttering because the card downclocks to stay under your definited maximum power usage.
 
Magic Carpet said:
Has anyone undervolted Kepler's idle performance state? It seems a little tricky.
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to do what? save 1 watt at best?

the 770 uses much lower idle speed and lower voltage over the 670/680 and still consumes only 1 or 2 watts less at idle.
 
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toyota said:
to do what? save 1 watt at best?

the 770 uses much lower idle speed and lower voltage over the 670/680 and still consumes only 1 or 2 watts less at idle.
Click to expand...
Why did you even bother to reply? If you do not have the answer to my question. This is about knowledge.
 
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Magic Carpet said:
Why did you even bother to reply? If you do not have the answer to my question. This is about knowledge.
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well here is some knowledge for you. its STUPID to even bother with the idle voltage as you will not save anything by doing so unless you think saving possibly 1 watt is worth it. 🙄
 
I stumbled upon this a few days ago because my card rattles at P08 state and is only quiet in p0 state and intermediate states, I'm still experimenting with this. It's acting really weird and I could get the voltage all the way down to .887V at load but it crashes under windows. I'm trying to find the most power saving and quiet 2d clocks that way so far no success.
toyota said:
to do what? save 1 watt at best?

the 770 uses much lower idle speed and lower voltage over the 670/680 and still consumes only 1 or 2 watts less at idle.
Click to expand...
Click to expand...

It has its uses, see above. To be fair normally it would be useless but I have a defective unit and it can help manage my card in 2d settings.
 
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Lepton87 said:
1. I can't
2. It works it just rattles at idle, they don't advertise idle noise so they have no obligation to send me a non-rattling card.
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Yes, it's called selling you a working part that is satisfactory to your needs. I'm not sure how or why you bought a $1,000 part with no warranty, but wow, that's unfortunate.
 
Doesn't work on my GTX 670. PT80%=914Mhz, PT100%=940Mhz PT122%=1110Mhz
Offset+80

Running unengine valley benchmark.
 
So at 80% you are only 26mhz short.

With very slight increases to the core clock you should be able to get stock performance with a lower voltage.

Depending on chip you might need to very slightly increase power target from 80 but you shouldn't need to go past 85% while maintaining at least stock performance
 
My GTX 780 idles at 26C and barely makes any noise. It runs at around 60C-65C at load, and that is heavily overclocked. (7ghz VRAM, 1202 on core) I guess I could see value in this, totally not my thing though.

Just curious - was this more for the "experiment" factor or did you feel a genuine need to lower heat output and such?
 
willomz said:
So at 80% you are only 26mhz short.

With very slight increases to the core clock you should be able to get stock performance with a lower voltage.

Depending on chip you might need to very slightly increase power target from 80 but you shouldn't need to go past 85% while maintaining at least stock performance
Click to expand...

Yes, but I don't want stock performance, I want moar!!!! 🙂
 
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