Though I'm not a fanboy of OCZ it's more than adequate for up to 2 GTX 580's; OCZ's are notorious for coil whine.
For now, run as I mentioned AIDA64 or Prime95, also have running Real Temp (CPU) and HWMonitor (MOBO and GPU(s)). I'm trying to separate the GPU out of the equation with stressing. If the Temps are getting high then I'd evaluate air flow, I prefer negative pressure in the case and front to rear/top out.
Q - What case?
Q - Are you OC'ing either the CPU and/or GPU(s)?
Further, look at the Event Manager to see exactly what [+] Critical errors are listed. Anything more the 41/63's are very helpful; see -> http://i1013.photobucket.com/albums/af254/Jaquith/Event_Manager.jpg