Degrading Graphics Card Upgrade

[Calamorn]

While I'm not completely new to the world of building a PC, I suspect you gentlemen will find me an answer much more quickly than I can.
Awhile back (Around when ICC was current) I was gifted a computer. Not the worlds best, but it gets the job done.

I'm having an issue. The fan on the GPU is degrading, and while under load the temps only hit around 40-45C for the rest of my computer I'm finding my GPU steadily climbing each day. I wouldn't mind seeing 70-80C under load, heck, not even the low 90's would worry me too much. I wouldn't be happy with it, but I could deal with it. Under load I'm rather regularly seeing 108-110C and my computer is shutting down. Seems the fan has recently decided to kick the bucket.

I'm looking for something that works with the existing parts, I wouldn't mind the fact that something else is going to be the bottleneck, but I plan on building a full large tower in about half a years time. So what I'm really looking for now, is something that's going to give me at least the same results as my current GPU or better, without having to upgrade anything else.



Here's the short of what I have.
A 400w power supply, 4gig ram, midsized tower, stock heatsink for cpu.
Mobo: Foxconn M61PMV
CPU: AMD Athlon 7850 Black Edition
GPU: NVIDIA DeForce GT 240

[Lolkrayd]

your best bet is probably a radeon 7750

[Butler to Baby Sloths]

Radeon HD 7770. The 7750 is an HTPC card, and not suitable for any real amount of modern gaming. Will set you back about 100-120 dollars.

[Faithh]

Radeon HD 7770. The 7750 is an HTPC card, and not suitable for any real amount of modern gaming. Will set you back about 100-120 dollars.

A 7750 is currently fine for every game at low settings.