Just bought a brand new CM GX 750W PSU, after 2 days of use, an on and off electrical buzzing occurs, it's not constant. But after i shut down the com a less loud buzzing sound is heard from the psu I'm sure of it.It's non-stop, i have to switch off the main socket to eliminate the noise. What is happening?
It is possible you got lucky, or it is possible that CM brand labeled another manufacturers PSU for your 390W unit; CM is a tier 3 manufacturer. Seasonic, Corsair, enermax, XFX are all tier 1. As a tier 3 manufacturer, I wouldn't expect flawless operation, but I'd bet the protection circuitry is probably present, so when the unit does go, it is much less likely than some no-name brand of frying your computer, though I'd replace it anyway.
The buzzing could be (high pitched) a bad capacitor, (any pitch)a bad fan bearing, or (low pitched)winding vibrations. If it is intermitant, it's prob winding vibrations, which won't hurt anything as long as the coating doesn't wear off of the windings.
People should stop riding the Corsair / Antec / Seasonic Bandwagon.
Yes, corsair is a great brand that has few faults, but all other brands have faults in at least 1 line of PSU - For Seasonic thats cost, Antec has Basiq power which is terrible, and XFX have PSU's that get 5-6 from Jonnyguru or hardwaresecrets.
Cooler Master have some good PSUs and some terrible PSUs.
e.g. Silent Pro Gold's are rocking out with 9~9.5 /10 from Hardware/Jonnyguru.
They'll also have some bad ones, but the only brand u can really buy w/o looking at the model except for the specs is corsair at least for now.
Other brands can have goodies too - and they'll often be cheaper