Is it safe to edit the GPU's BIOS to undervolt?

[Vasllo]

So, today I started overclocking my Zotac 970 and noticed that it was using a whole lot of power, 165-170w stock (1304Mhz) while my friend's acx 2.0 970 was using about 155w at 1367Mhz. That was causing it to bump against Power Limit even stock on Furmark.

 

I accidently discovered a way to make it work better, reducing the Power Limit to cause voltage throttle, and it's now running at around 1470Mhz at 1.137v (from 1.2v). The issue is, controlling it with Power Limit causes both the voltage and clock to fluctuate quite a bit, and I would rather let the power consumption fluctuate and keep a stable voltage and clock, but my GPU doesn't have voltage control, so I suppose BIOS edit is the only way?

 

Also, what would be a good voltage? I was thinking somewhere between 1.14 and 1.15 to keep a stable 1.500Mhz clock (I've achieved 1.540Mhz in Furmark although had to lower to 1.520Mhz on GTA V to remove artifacts).

 

The biggest question mark here for me is: How can I recover from a bad BIOS in case it happens? My CPU has no iGPU.

[Jurrunio]

Does your card have a BIOS switch? If it doesnt then it will be risky.

[Vasllo]

1 minute ago, Jurrunio said:

Does your card have a BIOS switch? If it doesnt then it will be risky.

Nope, it's the simple dual-cooler Zotac model.

 

What I was wondering is, let's say I lower the voltage to 1.14v, if I open Furmark and it's unstable, will it just crash the application like it happens when I undervolt with MSI Afterburner? And if it locks the system, will it be able to boot back in since the boot won't demand much from the GPU so the voltage won't be a problem? Or is it all going downhill if it crashes and there's no way back?

[Jurrunio]

4 minutes ago, Mateus Campello said:

Nope, it's the simple dual-cooler Zotac model.

 

What I was wondering is, let's say I lower the voltage to 1.14v, if I open Furmark and it's unstable, will it just crash the application like it happens when I undervolt with MSI Afterburner? And if it locks the system, will it be able to boot back in since the boot won't demand much from the GPU so the voltage won't be a problem? Or is it all going downhill if it crashes and there's no way back?

If the bios flash is successful, then you can toy with the settings as much as you like. If it crashes, just take away the undervolt settings in the software (Afterburner). What worries me is a failed bios flash, which will render the system unless since you dont have another graphics adapter.

[Vasllo]

1 minute ago, Jurrunio said:

If the bios flash is successful, then you can toy with the settings as much as you like. If it crashes, just take away the undervolt settings in the software (Afterburner). What worries me is a failed bios flash, which will render the system unless since you dont have another graphics adapter.

I would just change the voltage and that's it, to a voltage I already know that works (plus some margin), because I have no control of voltage in Afterburner, I'm inducing it to lower the voltage indirectly.

 

The chances are probably slim that it won't work, but I guess it's better to have fluctuating clocks and voltage than risk bricking it.

[Mick Naughty]

Wouldn’t be worried about flashing it. Rare that cards get bricked. 

[Vasllo]

7 hours ago, Mick Naughty said:

Wouldn’t be worried about flashing it. Rare that cards get bricked. 

Even if I change the voltage myself? I've thought a bit about this and I think my real doubt is: If I flash it with less voltage, will it just crash apps when I open them and run windows and stuff fine like it happens when I limit the voltage in MSI or is it gonna behave differently? Like not even opening Windows (which would be a real problem for me since my MOBO has no video output).

[Vasllo]

8 hours ago, Mick Naughty said:

Wouldn’t be worried about flashing it. Rare that cards get bricked. 

Is it actually possible to flash the BIOS without another video adapter? Because I see people saying you gotta unninstall all drivers and also disable the adapter (wouldn't I have no video then?)

[Mick Naughty]

1 hour ago, Mateus Campello said:

Even if I change the voltage myself? I've thought a bit about this and I think my real doubt is: If I flash it with less voltage, will it just crash apps when I open them and run windows and stuff fine like it happens when I limit the voltage in MSI or is it gonna behave differently? Like not even opening Windows (which would be a real problem for me since my MOBO has no video output).

Assuming you can configure a file to have less voltage through ththe appropriate steps, you won’t have an issue, ever. Just because the voltage is lower, doesn’t mean the core speed won’t fluctuate, unless it’s hard clocked and you get rid of gpu boost while you’re in there. 

[Mick Naughty]

Just now, Mateus Campello said:

Is it actually possible to flash the BIOS without another video adapter? Because I see people saying you gotta unninstall all drivers and also disable the adapter (wouldn't I have no video then?)

I’ve flashed 3 cards at the same time on one rig. Done it every way pretty much. Never had an issue or needed another adapter for video.  Real simple and quick process. 

[Vasllo]

1 minute ago, Mick Naughty said:

I’ve flashed 3 cards at the same time on one rig. Done it every way pretty much. Never had an issue or needed another adapter for video.  Real simple and quick process. 

Alright, I think I'll try it. Did you use nvflash to flash the BIOS?

I'll just research a bit more about voltages, because there are like 78 steps there, I just lowered all that were above 1.125mV, which is my target (which I might lower to 1.100mV), not sure if that might fuck something up but makes sense to me.

[Mick Naughty]

yes I use nvflash, don’t know of any other programs. As long as the core isn’t going above the same step of voltage. As in letting the card still try to run where is used to when it had its stock voltage. Could crash under hard load. 

[Vasllo]

Update: Flashed the BIOS without issues (thanks Mick Naughty), actually ended up flashing 3 times to fine tune the voltage. In the end I got it to run stably at 1480Mhz (it would work up to 1540Mhz in Furmark, but cause artifacts in GTA V any higher than 1480Mhz) with -75mV. Stress tested it in Furmark and Heaven for half an hour more or less each and it seems stable. Not only it's not running 174Mhz higher than stock but is using 20w less power.

 

Funny fact: After lowering the voltage from 1.2v to 1.125v, the clock instantly went up to 1417Mhz, which is pretty impressive and shows how much the power limit was holding it back.

 

Thanks again for the incentive and all the help, Mick