Pulling out the TES 1350A Sound Level Meter we find ourselves quickly yelling into the top of it to see how loud we can be.
After five minutes of that we get a bit more serious and place the device two CM away from the fan on the card to find the maximum noise level of the card when idle (2D mode) and in load (3D mode).
Overclocked the HD 6870 from Sapphire is more audible. This isn't much of a surprise as we found that the HD 6850 from HIS was also louder when we overclocked. It's clear that the fan is working a little harder.