Basically, compare it to mediocre 800W units
In that power range, we have:
COOLER MASTER Silent Pro Gold Series RS800-80GAD3-US 800W ATX 12V v2.3 / EPS 12V v2.92 SLI Ready CrossFire Ready 80 PLUS GOLD Certified Modular Active PFC Power Supply - $159.99
SILVERSTONE Strider Gold ST85F-G 850W ATX 12V v2.3 / EPS 12V 80 PLUS GOLD Certified 100% Modular, Active PFC Power Supply - $144.99
OCZ ZX Series 850W Fully-Modular 80PLUS Gold High Performance Power Supply compatible with Intel Sandybridge Core i3 i5 i7 and AMD Phenom - $149.99
COOLER MASTER Silent Pro Hybrid RS-850-SPHA-D3 850W Intel ATX 12V V2.3 & SSI EPS 12V V2.92 SLI Ready CrossFire Ready 80 PLUS GOLD Certified Modular Active PFC Panel Power Supply with Fan Control - $159.99
Basically this power supply is nothing to write home about.
Also, doesn't this thread belong in Mining -> Hardware?