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.
As for noise levels, this is really the only difference between both BIOS options. The Silent BIOS spins the fans at 1700rpm, compared to 1900rpm for the OC BIOS, and accordingly it is about 3dBa quieter based on our testing. It’s still not the quietest card we've tested, as the Silent BIOS itself comes in 3dBa louder than the MSI Gaming X Trio. It's certainly not loud however, and for the vast majority of users installing this in a case, it certainly wouldn't cause any problems.