I would go with a 700 watt psu a good brand like corsair or ocz my favorites
no clue what you are talking about or how you achieve these numbers other then making them up but you are incorrect.
with an ATI 5850 and phenom II CPU set up you won't break 350w at peak load. you can even OC the CPU and stay safe
Test System Specs & 3Dmark Vantage
Core i7 Test System Specs
- Intel Core i7 965 Extreme Edition (Overclocked @ 3.70GHz)
- x3 2GB G.Skill DDR3 PC3-12800 (CAS 9-9-9-24)
- Asus P6T Deluxe (Intel X58)