Well, before I go through RMA, let me check if it could be my fault instead of the PSU. The heatsink I'm using is a Zalman 9700, this one is quite big and it's sitting just underneath the PSU. The fan of the PSU is pointing down so a priori it may be taking hot air out of the heatsink straight into the PSU.
Could it change if I just put the fan up? I doubt this is the case cause I tested running the system quite hot from a cold boot (booting and then running prime factorizations for quite a while) and the "noise" didn't change at all (I can't measure RPMs on this fan).
Should I apply anyways for RMA or should I unplug everything and change the fan up?
EDIT: wait a second, I just read some threads in the RMA subforums (I probably should move this whole one there) and from those examples I guess that I have to have my system down until I get the PSU fixed? this sounds kind of ridiculous, but anyways, is this how RMA works?