Under-volting the 970 or 980

[BonzaiDuck]

Somewhere . . . maybe in these forums . . . I THOUGHT I saw indications that somebody had actually under-volted their 970 or 980 card to get the higher clocks attainable under the ceiling imposed by the 110% power-consumption cap.

Is that true? Some of the reviews and guides I looked at suggested that "stock" for the 970 was about 1.205V, and it could be raised to approximately 1.25V.

But I'm intrigued with any possibility to go in the opposite direction . .

 

[Borealis7]

nVidia does not officially allow you to mess with the voltages of its' cards. you can, however, set the power limit to negative (upto 20% IIRC) and in that sense "undervolt".

even the voltage bar in AB/PX/whatever does not really raise the voltage, it only suggests to the card whats the minimum voltage to use in various power states.

so unless you flash a new bios with altered voltages (like has been demonstrated for full GK110 GPU cards - GTX780TI and such) you can't do anything about it.

i haven't looked into the issue for a while, maybe someone did find a way to do it without flashing, but i doubt it since nVidia want to do the OCing for you instead of letting you muck about and ruin their cards.

 

[Pneumothorax]

Undervolting via bios flash comes with a very high risk of bricking your card. Not advising it, but if you have Sandy bridge or later cpu with igpu you could re-flash with the original bios (hoped you backed it up) to resurrect the card. Considering how hard Nvidia is pushing efficiency, I really doubt you're going to get much mileage by undervolting.

 

[Magic Carpet]

You can shave off some 20-40w under load, if you do that right. But you can also reduce the power target, albeit you would lose some speed in the process. At any case, bios modding is a must. Haven't played with Maxwell yet, but there is Google, you know.

 

[BonzaiDuck]

I have the MSI Gaming 970. Afterburner has a feature for unlocking the voltage, which can then be adjusted in the overclocking window of the app.

I think various reviewers had shown the stock voltage under ~100% GPU usage would be 1.205V, and that it could be adjusted UPWARD to about 1.25+V something.

But if voltage can be reduced slightly (and it can with the slider unlocked), the power consumption could be reduced a tad below the maximum 110% limit -- if only the card remains stable at a near-1500Mhz top speed.

I think at this point, however, with the ~200Mhz OC you can achieve with these cards without touching the voltage, further tweaks are going after slivers and grains of rice.

 

[Magic Carpet]

@BonzaiDuck

There is no question, if you are going to leave your card at factory clocks, you can reduce the voltage and save a bit on power. I've done that on my Kepler/Fermi/GCN cards.

How much, nobody knows, you have to find that out for yourself. If your stock voltage is 1.205, you could start at 1.150. I would only use games for stability tests, though.

 

[tviceman]

I don't know how Maxwell works (I have a 980 but don't care to mess around with voltage adjusting since it does so little), but with Kepler you could not undervolt via sliders with any utilities. Power limit was the only way to lower voltage, and that wasn't a sure bet. Flashing a custom bios would allow the card to "undervolt" but of course came with all the usual risks.

 

[Magic Carpet]

Power limit was the only way to lower voltage, and that wasn't a sure bet.

This way you also lose speed, which ruins the purpose, of getting more perf per watt. I firmly suspect, Maxwell works similarly.

Flashing a custom bios would allow the card to "undervolt" but of course came with all the usual risks.

Yeah, Kepler required a bios mod.

IMO, GCN cards were much easier to tame and control with the volts. Love them for that.

 

[BonzaiDuck]

Generally, if you raise the clock and power-consumption bumps up to the 110% limit, then the GPU automatically throttles back.

I'd think the trick is to find the clock-speed where power-consumption just tops out below that 110% limit. If voltage can actually be lowered, then there are a few extra clock cycles to gain.

I'm fairly new to this -- like I said, I'd dabbled with it back in my GTS 8800 days. Didn't fiddle with the GTX 570 card, or the 780. I'm still wondering if I lost my mind for not looking around more for a used or stray 780, but I was star-struck by the news about Maxwell.

Over all that time, the software made it easier to overclock. It seems more like a marketing game. They make the card to almost guarantee that it will overclock so far within the power-consumption limit, so any noob who does his homework should find the setting at 1500Mhz core and 8000Mhz memory easy without touching voltage (if indeed it can be touched, but I explained that.)

Still, the reviews concluded that these were "very overclockable" to that limit. Of course the reviews were stellar, but the latest gripe over the 4GB shows a lot of things, no less about the complaints and customer perception than about "marketing people." And I still think two of these cards in SLI is a good bang-for-buck compared to two 980's.

Maxwell did live up to the promise. I figure with a stock max power-consumption spec of 145W, the OC puts it close to 160. I think you can run two of these bad boys with a 550W PSU with plenty of room to spare for "extra gadgets" along the way.

 

[Magic Carpet]

Generally, if you raise the clock and power-consumption bumps up to the 110% limit, then the GPU automatically throttles back.

If you are not thermal or power limited, this shouldn't be happening. What I found out with my GTX 670, that at lower temps, I had the maximum boost (1254 Mhz to be precise) rate maintained 99% of the time, sure my power limit was raised to 117%. Pretty sure, with a bios mod, you should be able to raise the power limit beyond the 110%.

I'd think the trick is to find the clock-speed where power-consumption just tops out below that 110% limit. If voltage can actually be lowered, then there are a few extra clock cycles to gain.

This makes sense, trial and error is what I say, and have a spare card nearby, should the flashing fail.

I'm fairly new to this -- like I said, I'd dabbled with it back in my GTS 8800 days. Didn't fiddle with the GTX 570 card, or the 780. I'm still wondering if I lost my mind for not looking around more for a used or stray 780, but I was star-struck by the news about Maxwell.

Fermi was fairly easy to tame though, no turbo boost, you could change voltage on the fly. Well, the big Kepler is more like 290/290x power consumption wise. Maxwell is much more efficient in using available resources, not a big loss for you, I think.

Over all that time, the software made it easier to overclock. It seems more like a marketing game. They make the card to almost guarantee that it will overclock so far within the power-consumption limit, so any noob who does his homework should find the setting at 1500Mhz core and 8000Mhz memory easy without touching voltage (if indeed it can be touched, but I explained that.)

Of course, they could increase the stock clocks instead, would have been better, especially for the people, that are not comfortable with manual overclocking. I suspect the reason was simple, though. Power consumption. They just found the sweet spot and decided to call it a day. And whoever needs more, they can OC.

Still, the reviews concluded that these were "very overclockable" to that limit. Of course the reviews were stellar, but the latest gripe over the 4GB shows a lot of things, no less about the complaints and customer perception than about "marketing people." And I still think two of these cards in SLI is a good bang-for-buck compared to two 980's

It's still a well-balanced card, if you can live with its obvious shortcomings.

Maxwell did live up to the promise. I figure with a stock max power-consumption spec of 145W, the OC puts it close to 160. I think you can run two of these bad boys with a 550W PSU with plenty of room to spare for "extra gadgets" along the way.

In my experience, the official TDP numbers don't mean a lot. There are similar cards with the same 970 silicon that would consume different amounts of energy, up to ~50w difference, easily. It's not just voltage, clocks, silicon. Its everything including the power circuitry/PCB design, that affects the total power consumption. Obviously, the reference 970/980 would be the most efficient and easiest on the power bill (out of the box).

I would firmly say, that the reference 970 (sold in Bestbuy) and the reference 980 are the best for 2-4 card configs. From performance-per-watt perspective as well. With down-volting / down-clocking, you could tweak any card to find perfect balance of "speed and acceleration", though. Just takes time.