Is there any reason not to run your fans on "performance" mode (IE, higher RPM) besides the noise? I can deal with the noise if it keeps my CPU/GPU cooler during gaming. My computer is rarely on for any other reason. The only reason it might otherwise be on is for video editing...and, well, that needs even more cooling.
I mean, it doesn't add to the CPU load, does it? IIRC, my CPU fan is directly getting power from the PSU, and has one USB 2.0 header plugged into the mobo. The fans on my GPU are built into the card, so it's technically plugged into the mobo, but of course the GPU is also plugged into the PSU.
(for reference I have an H80i which I'm using Corsair Link to boost my fans up to performance).