We take our noise measurements with the sound meter positioned 1 foot from the graphics card. I measured the noise floor to be 32 dBA, thus anything above this level can be attributed to the graphics cards. The power supply is passive for the entire power output range we tested all graphics cards in, while all CPU and system fans were disabled. A reading under load comes from running the 3DMark Time Spy stress test for 30 minutes.
Our acoustic testing shows a small but just about perceptible difference in noise levels when comparing BIOS 1 to BIOS 2. BIOS 1 is unsurprisingly the slightly louder of the two, peaking at 38.4dB which is still a very good result. BIOS 2 saw noise levels come in about 1dB quieter, which is an even more impressive result.
To illustrate the small difference between the BIOS in terms of fan speed, we saw BIOS 1 run the fan at 55%, or 1270rpm, when BIOS reduced this to 50% fan speed, or 1150rpm.