My wife has a 24" iMac with an ATI Radeon HD 2600 Pro graphics card from back in 2007. And I was wondering if I can get an upgrade for it. If so, what is the best graphics card that I can get that will fit it?
1997? Maybe 2007? The best video card for that iMac is the NVIDIA GeForce 8800 GS. These go for about the same price as that iMac's current value. They are the best of three video cards your iMac can take. If you do get one, you must use the Nvidia heatsink that comes with it. The ATI heatsink is not compatible.
I would consider selling your wife's iMac and buying another one.
The new piece of 8800GS costs same money as your wife's iMac.
And when you got it installed - the new card will fry your iMac in less than a year.
The choice is yours 🙂