edit: - Ive just seen your psu guru man, your clearly paraniod lol
http://www.hardwaresecrets.com/artic...ly-Deliver/534 "500W" fails at 265W
http://www.jonnyguru.com/modules.php...Story&reid=187 "1050W" fails at 550W
http://www.hardocp.com/article/2010/...supply_review/ "650W" fails at 490W (probably a 300W unit)
http://www.jonnyguru.com/forums/showthread.php?t=6714 "680W" fails at 250W
http://www.jonnyguru.com/modules.php...Story&reid=188 "750W" violates ATX spec at 450W
Power supplies aren't like other computer part industries. It's nearly completely unregulated. Many aren't UL certified, almost none are FCC certified, just "FCC compliant". There's no legal definition of what "wattage" is in regards to power supplies, so they're free to make numbers up as much as they want. Why go to the effort of desiging and building expensive high-end power supplies when you can take an old design from 1998, build it as cheap as possible so it can barely do 250W and has no filtering or surge protection, and stick any label on it, from 250W to 750W or beyond. People will still buy it, outside of enthusiast circles.
That's why this forum needs PSU gurus such as myself and Tator Tot, to distinguish the crap from the good. And you can't just go by brand--many "good" brands will frequently take a crappy power supply and overrate it and sell it using their brand name to mask the crap. Thermaltake and CoolerMaster are the biggest offenders here; Corsair is starting to get into that themselves.
If you're willing to blithely accept whatever is printed on the label, then I recommend the Echostar 680W, and may your computer rest in pieces.