500W or 600W ?

Antec EA650 650W ATX12V Ver.2.2 / EPS12V version 2.91 SLI Certified CrossFire Ready 80 PLUS Certified Active PFC Power Supply - Retail $79.99
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http://www.newegg.com/Product/Prod [...] 6817371015

or

OCZ StealthXStream OCZ700SXS 700W ATX12V / EPS12V SLI Ready CrossFire Ready Active PFC Power Supply - Retail $89.99
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http://www.newegg.com/Product/Prod [...] 6817341019

either shuld be fine...well actually more than u require...
But wat budget are u willing to spend?

so if i get a Corsair 500W, will it run at 70%-90% all the time?

+1 what chookman said.

My personal preference is for Corsair psu's. Corsair has always earned high marks in technical reviews and comparisons. The psu's are high quality, stable, and very reliable.

AdLi - It looks like that web page needs to be updated with a few newer pc components.

I gave it a shot and came up with 218 watts at idle which pretty much matches what chookman posted. In your original post you specifically stated that you were not going to overclock or use multiple video cards so a high quality 500 watt power supply can handle your system even under full load without any problems.

Also whats better, a single 41a rail a la corsair vx 550w or three rails at 25a?

I'll be using crossfire with 4670/870's if that makes any difference

EDIT: would it be better to go with the PCP&C silencer 750w with a 60a single rail?

+1 for what the Animal said.

There have been quite a few threads, discussions, and articles about single rails and multiple rails. If I understood them correctly the concept of multiple rails is mostly marketing hype. A majority of psu's advertised as having multiple rails actually have just one large single rail. The best advice is to purchase a high quality, stable, reliable power supply that works and be happy.

Corsair and PC Power & Cooling consistently earn high marks in technical reviews and comparisons. Those two brands are often recommended by veteran posters.