Motivation

Ampere cards pull more power than ever before. However poor overclocking performance might be an indication that Nvidia already pushed the silicon to its limit. Hence a small underclock at a greatly reduced voltage might actually reduce power consumption significantly, whilst having almost no effect on performance.

Testing Setup

The only important factor here should be the RTX 3080 Aorus Xtreme, all benchmarks will be exclusively GPU-bound, so no need to discuss the rest of the setup.

This GPU can draw upto 450W reliably at 1.093V, so a 450W overclock has also been included. I couldn't get voltage to drop below 0.725V, so that is the lowest result, I could not keep it under 200W without power throttling the card, so the 180W result is significantly worse due to it throttling hard even at 0.725V.

This is very inefficient, I'd only go as low as is possible using 0.725 (so 200W), anything below that and you start to hand in buckets of performance for droplets of power consumption.

Results

Conclusion

Clearly the 3080 handles 320W well, this being the stock setting for many RTX 3080's. 370W still gains some ground, however afterwards little gain is to be had. The only game that consumed 450W and gained something significant was RTX Quake II (and Minecraft, not tested), likely because the RT cores are being fully utilized here as well as all shader cores.

So my take would be that undervolting to 240W can be done rather efficiently, whilst anything lower will quickly cost too much performance.