What kind of power supply do i need?

no, you're going to need a lot more than 250W. depending on what other drives, etc you're putting in, i'd say 500W-600W minimum. a larger power supply allows your computer to run more efficiently because it's not maxing out the power supply all the time. if you're building this for primarily gaming, i'd even go so far as to say 750W-1000W isn't too much.