I upgrade GPUs and CPUs on a revolving cycle; generally I keep my previous GPU when I upgrade my CPU, and vice-versa. Last year I bought a Core i5-3570K (which I have humming along at 4.4Ghz), so I'm still running my prior MSI N460GTX Cyclone 1GD5/OC card. Last year, though, I sort of broke my own rule and picked up a second N460GTX 1GD5/OC card on eBay for just $50. Running both cards in SLI at 810Mhz core, they're individually the same essential thing as a GTX560 (336 Fermi cores, 256-bit memory), so I typically tell people I'm running "GTX560 SLI" to keep things simple.
In SLI, as long as I don't have SLI-specific problems or run out of video memory, I can run basically anything at 60hz at 1080p. These two cards crush Far Cry 3, demolish Borderlands 2, annihilate Skyrim (even with the HD texture pack), and destroy Battlefield 3. They laugh at Blacklight: Retribution and sneer at Dark Souls (with DSFix) and anything less.
The curious part is that recently, my second N460GTX has become kind of flakey in SLI, so I put it in my wife's machine (where it works fine, hmm), and even in single-card mode, my old N460GTX -- nearly 3 years old now -- still runs more or less everything fine in 1080p. I get ~70FPS in Blacklight: Retribution, and while I had to disable ENBSeries, Skyrim still runs vsync'd too. (Using my ENBSeries preset, which I could run at 60Hz vsync with SLI, does drop my FPS to ~20s in single-card mode, though.)
In fact, this single card (@822Mhz since it runs cooler being the only GPU) is so fast, I've recently begun to revise my recent urgency in GPU upgrade. I panicked a little when my second GPU "died", and I was ready to plunk down $350 for a 7950 or GTX670, but I think I might wait further still and pick up a 700-series or 8000-series, especially given the recent driver foibles with the 79xx and the gimpy memory bandwidth on Kepler.
tl;dr I run everything maxed-settings-1080p @ 60Hz Vsync'd on a single GTX 460.