Hey can someone tell me how do I know what pc case to buy. I seen cases on ebay and they have different watts and how do I know how many watts to get. and if that depends on the motherboard.
That'll tell you all you need to know. Most importantly, though:
Wattage is great, but amperage is more important (on the +12v rail particularly). You can have all the watts you want, but if they're not going to the right places....
video card will be the main reason to get a big watt power supply, like 500 for anything new in the video card ago. like me 7800 gt, i gave my computer a 550 watt ^^