Originally Posted by reeves

He should have an Apple Hardware test disk. Comes with all Macs. I'd suggest he run it to see what happens.

Alright, I'll get him to try that. Thanks.

just get 2 evga 280gtx sli them and your set for the next 10 years.

something wrong with one of the drivers perhaps? (I dunno anything about osx though)

Just to pitch in a little
The GTS250 is the same as the 9800GTX+ which is about the same performance as an ATI 4850.

Before buying a card make sure you know what kind of connectors it has on the back, 2DVI, 1DVI 1VGA, 1DVI 1HDMI, etc etc. You will probably want 2DVI.

Also make sure your power supply can handle the card, make sure you check the wattage. If you are planning on getting two cards (not necessary as a single HD4870 destroys the 7300GTs even if they were in octa-sli) then make sure you have enough 8pin/6pin power connectors on the power supply.

Final thing, I haven't owned a mac in a while, but I'm pretty sure you cant just pick up any hardware you want and pop it in, you have to make sure that apple has supported drivers for it, and that would mean a lot of research and possibly buying specific mac-compatible hardware.