Im not sure if I need to get a new PSU for the next build I'm doing, or if I can reuse the current one I have. I'm planning on building an i7 920 gaming computer for $1,000. How much wattage should I need? Currently I have a 600W OCZ GameXstream
check using that, throw on 30% capacitor aging as that will reduce the load on the PSU to the efficiency band and extend the life of the PSU. Your 600W PSU will be sufficient for any single card setup(this does not include X2's and the GTX295) but if you want to run crossfire or SLI you may need a new one.
I haven't decided what I'm going to do about a video card. According to the article here that lists best cards for the money, I should crossfire 2 4870's. Or maybe get an HD 5850. Still have to do more research for that one. If I Crossfire I will need a new PSU.
For that site that you linked, if I did everything right then my 600W should be alright. It lists 576W for my needs. But thats with system load at 90%. If I bump it up to 100% I would need 640W.