Hi DUIT!!!!
Definitely upgrade to an nVidia cad for folding.
I run two GTX 460's from EVGA which can be had for around $100.00.
They average around 15,000 ppd.
I recently bought a GTX 570 which on many work units gets 33,000 PPD but in this 80XX series only gets around 25,000 PPD
They do run HOT! At least this one does.
Yes, I overclock my cards. A simple matter of installing EVGA precision tools and bumping up the SHADERS gradually.
There are cards like Sun's GTX 660 Ti's which scream.
I got my 570 on sale at a great price of about $160.00
Normally you will pay about $240 for this card.
The maker is ZOTAC.
I prefer EVGA video cards. Better warranties and imo a better card.
Of course there are cards in between as well like a 560 Ti for example.
Any is a good choice. Ask away and we will try to answer!
Take care,
micro...