Right now I am really trying to play left 4 dead. the first thing i did was buy a geforce 7900 gt, well it turns out my power supply isnt big enough to run that type of card. Im using an acer m5100 that has a puny 250w power supply. I found a decently priced 500 watt one but I just need to know what I should be looking for in the realm of rails. some say it has 2 12v rails and some say single. What do I need or how do I find out. Any help would be greatly appreciated.