Look at what cost 750W devices from established manufacturers - already then you should put the quality of this device in question.
In addition, the fewest ever need a 750W unit, rarely for later Aufrüstvorhaben (as many reasons for its decision). Newer hardware generation are usually more efficient and often consume more than older components. 500W rich even for the vast majority of "gaming" PC. I'm using for years a BQ Straight Power E9 with only 400W - which has always problem cards like a GTX 570, 7950 or GTX 770 powered.
There is even less money for good devices that keep their promise and come with decent / good quality therefore. Some alternatives to Combat Power:
EVGA 500B Bronze 500W
Coolermaster 450W G450M
be quiet! System Power 400W or 450W 7
Corsair CX Series Modular CX500M
be quiet! Straight Power 400W 10
Corsair CS Series Modular CS550M
