I think 300W is the minimum for X1600XTs. You could try it out (I'm assuming that it wouldn't fry anything), but I'd really recommend replacing that power supply. Who knows, though...my 7800GT was running off of 14 amps on the 12V rail perfectly fine, and I was supposed to have 18 minimum. Though after about 8 months, my PSU blew, but I wouldn't think that that's the reason because it was running so well... Whatever. Assuming that it wouldn't fry anything (I'm sorry that I have limited knowledge of PSUs), I'd definitely give it a shot before spending ~$100 or $75 on a good PSU. I remember hearing 300W from somewhere.