24A? As in 24 amp? Holy crud! I don't have a big enough electrical hookup for that anywhere in my place! Max load on a 20 amp circuit is 80%, which is 16amp. You'd need 30 amp for just your video card!

Try a new power supply. If you have electrical skills, you may want to run a meter against your outputs, but if you needed me to tell you that DO NOT attempt it.

But then again, your video card my have just died because it was defective, hard to say.

Edit: My system, 880GTS, quad core, 4 disk drives runs off of a 400w PS with no issues. In fact, under heavy load, it barely crests 220watts at the wall.