New Computer

[Speedo]

I don't think it's ever been cheaper to get 2 of the slower cards rather than 1 of the faster ones.

Availability is also an issue, when I bought each upgrade, buying an extra card for SLI would have needed going to ebay or the like, older generations phase out pretty quick.

Once a new generation of GPUs comes out, it's almost never worth it to do an SLI/Crossfire upgarde. If SLI/Xfire would actually double performance it might be, but given the real world performance of the technologies, it simply isn't.

 

[Asher]

Once a new generation of GPUs comes out, it's almost never worth it to do an SLI/Crossfire upgarde. If SLI/Xfire would actually double performance it might be, but given the real world performance of the technologies, it simply isn't.

It depends on if the game is CPU or GPU-bound. On GPU-bound titles, it's pretty close to 2x.

Eg, FEAR @ 2560x1600 w/ 4x FSAA...
GeForce 8800 GTS: 17fps
GeForce 8800 GTS SLI: 34fps

Prey @ 2560x1600 w/ 4x FSAA...
GeForce 8800 GTS: 32fps
GeForce 8800 GTS SLI: 62.3fps

If it's CPU-bound, getting a much faster GPU won't help you much either.