Freezing Problem

[chinis]

I've got an idea as to what the problem is, but I want to make sure before I go out and buy a new PSU. My computer started freezing and then rebooting last night, and it only does it whenever i play FF after a few minutes. I can use the net and chat and stuff and it works fine. I tried swapping out the RAM sticks, thinking I got defective ones. Still did it with my old ones. Tried keeping the CPU cooler. It was running around 60-80 celcius, managed to keep it at 60. Still did it. So I noticed the box for my video card said I need a 400+ watt PSU with 26amps on the 12V rail. I looked up the PSU manual, and it says it has 2 12V rails. One is 15 amps, the other is 18 amps. http://www.dynexproducts.com/skins/skin_1/Topics/Documents/DX-PS500W_UserManual.pdf Do the amps add up or are they seperate? I'm guessing seperate, because I'm using 1 of the 12V connections for my harddrive and dvd player, the other for my vid card (each has 2 4-pin connectors). Could it be that I need a better PSU? I've been running it like this for months though and never had this problem, thanks.