Should I SLI my old video card or break down and buy a new one?

Hey Fluther,

I currently have a Nvidia GeForce 8600 GTX and am starting to get annoyed at it’s performance in the games department. (I don’t do a ton of PC gaming)

Mainly, my video card does the trick for what I want it to do. (it plays Starcraft 2, WoW, and Team Fortress 2 fairly well.) But I am a little concerned for The Witcher 2 (the first Witcher kinda chugs on my machine) and Diablo 3.

I’ll probably get a new computer within a year or so, so I’m a little reluctant to spend a bunch of dough on a new video card… but I’m not sure if getting a second 8600 will do the trick enough to make it worth it.

So basically, I’m not sure if I should get a second 8600 or get something a little newer.