I was considering a Seasonic X-650 650W ATX PSU for my GTX570 (single card), do you think i will be enough? Keep in mind that my system will be on 24/7 for the next 4/5 years.
As far as the cpu goes (i5, 2500K 3.3Ghz) I may or may not OC, but even if I do it will only be to 4.0/4.2Ghz.
Is the 650W ok or should I go with a 750W
A reference clocked GeForce GTX 570 has a maximum graphics card power of 219 Watts. This means that the graphics card itself will draw up to 18.25 Amps from the +12 Volt rail.
For a single GeForce GTX 570 graphics card system NVIDIA recommends a power supply with 550 Watts or greater with a +12 Volt current rating of 38 Amps or greater and at least two 6-pin PCI Express Supplementary Power Connectors.
The Seasonic X-series SS-650KM with its ability to produce up to 54 Amps on its +12 Volt rail is more than enough to handle a system with a single GeForce GTX 570.
My single rail 550W from 2007 can handle (and DOES handle) the GTX 570...... even without efficiency ratings (most run at +/- 80%) it goes 550W/12V = 45.833~ Amps. A split rail, you need to figure how many amps MAX per rail, but with 2 or more connectors to your psu even that gets evened out in most setups. You should be fine. Recommended for the GTX 570 is 38 amps. The only reason to max up to 750W/1000W would be for the future, if as you say you want to make it 4-5 yrs.. some stuff might come down the pipe. But hey, PSU's are cheap, so you can always do it later.