not sure what cheap is to you but I'm getting this PSU for my high-end gaming rig, think it's pretty silent.
Newegg.com - CORSAIR CMPSU-620HX ATX12V v2.2 and EPS12V 2.91 620W Power Supply 100 - 240 V UL, CUL, CE, CB, FCC Class B, TUV, CCC, C-tick - Retail