Undervolting
Undervolting
so i just got a 6700xt nitro+ and initially thought about undervolting, but then noticed the wattman power limit slider only goes up to 30%, not 50%. at 30% it won't let me go lower than 1125 volts, even if i try a bit less and it crashes. someone could help or give advice.
Have you adjusted the card's settings before using it? Is there a reason to lower the voltage? Does it generate excessive heat, forcing the fans to operate continuously? Undervolting helps minimize heat and noise while maintaining performance.
to address both of your concerns, yes i attempted the card without adjusting settings. the hot spot measured 107 degrees and 88 degrees at the apex, around 165fps.
You can try undervolting and it is helpful not only to lower temps but also to improve performance. Modern GPU's are very temperature sensitive and anything you can do to keep hot spot temps below 90-95C only serves to improve performance.
Arranging fans to blow cool air into the intake area of your GPU's coolers, or even removing a case side cover, can help a lot with temperature. This may be the reason you're seeing high temps (107C) and instability, especially if you have a glass-side case with a vertical mount GPU.
I'm not sure what voltages are attainable for a 6700XT, but my 6800XT likes to have a setting of around 1068-1081mV for gaming. It can handle one or two passes of TimeSpy benchmark as low as 1050mV at a fairly heavy overclock but it will start throwing a lot of math errors in GPU Folding@Home unless kept above 1081mV even at stock clocks.
But be a bit cautious when increasing the power limiter. While it will most likely handle being pushed up to the max allowed, if you do the GPU will hit hot-spot temperatures of around 90C sooner and then start pulling back on clocks. Test it with back-to-back TimeSpy runs to see when it's hurting and not helping. Maxing the power limiter is usually beneficial only if you have extremely good cooling for the GPU...something like liquid cooling...but people do it a lot and think they've done a trick since it might give a terrific score with one pass at TimeSpy.
Also, AMD has imposed a hard power limit on Navi2 GPU's in the BIOS which mean they they can not exceed certain settings. So if the board partner has already increased the power limit with their (sanctioned) OC model then you only get the remainder to the AMD imposed hard limit. That may explain what you're seeing. There are ways around this with
RedBiosEditor (RBE)
if you're really interested, but it's definitely hardcore.
And lastly, undervolting may seem a bit strange if you're also monitoring the GPU voltage when in-game where it might hit voltages well above what you set it at. The way it's been explained to me is it's more of an off-set adjustment for introducing a bias to the boost algorithm to make it not hit as high of a voltage in each P-state as it would have before. So it will still hit higher voltages but not likely to hit the max, 1150mV in my case with stock settings
Power limits and voltage adjustments are distinct concepts.
The 6700XT (stock) has a TDP of 230W, which might be slightly higher for the Nitro+ model. At full power (100% +0%), the card increases clock speeds until it reaches that power consumption. Adjusting the power limit to +30% means the boost continues until it hits 300W. The opposite applies if you lower the limit by -20%.
Undervolting involves changing the voltage settings to a lower value for each frequency. The vBIOS provides a table mapping voltages to frequencies across the band. Lowering the voltage reduces power usage at that frequency, allowing the boost algorithm to raise the frequency until it matches the new power cap.
Applying a fixed voltage reduction (like -100mV) across all frequencies is straightforward but may not always yield the best performance for each specific speed.
When using older tools like WattMan, there were around 7 key points to configure, making it manageable.
In contrast, MSI Afterburner for the 3060Ti displays about 100 points on a graph that needs frequent adjustments, which is quite inconvenient. Sometimes the voltage offset is mistakenly shown as a frequency shift (e.g., +150MHz), but the actual effect remains the same.
1000mV equals 2150MHz in this context.
Many people mix up undervolting with underclocking.
Initially, only adjust the power slider when you intend to overclock. The voltage reduction amount varies depending on your card, as each has its own tolerances. If you managed to get better results, you’re in a better position; otherwise, you’ll be limited to standard settings. In your situation, it seems like the latter. To reduce temperatures, examine the fan settings. On my card, for instance, the auto fan speed is capped at 70% RPM. My card rarely exceeds 65°C, so I’m not concerned there, but if your card has a fan speed limit, you can cool it down by removing it.