I'm impressed.
Do you play other games on that res, and if so, is the performance generally okay?
It still impresses me tbh, I bought my second 580 as I fancied trying SLI and GTA V struggled a bit with just one and it spread from there, I like to buy from the MM, the monitors all came from car boot sales(!) very much a what can I build for buttons project.
GTA V, mostly high settings, reflections on ultra with MSAA (sure they look better like that!) textures normal, I'm not at home now to check (or force any more video's upon you!) 40 -50 fps is my norm even with distance scaling quite high.
Battlefield BC2, 3 & 4, all run maxed out (I lower textures on 4 mind you) I do get momentarily slight pauses on 4 on the Dragon Valley map which I don't get in others, I assume I must be hitting a VRAM limit.
Star Wars Battlefront runs beautifully on mainly high and ultra settings again, I lower textures as I assume I must be pushing my VRAM to the limit and then some!
Mid 40's to high 50's in Project Cars, F1 2015 runs very well, 70+
FSX is low 30's (quite normal for FSX) but with most other settings maxed out, it's very smooth and fluid which is crucial especially with faster jets.
Thus far though, yes, all my current games run @ 5760x1080 very well given you'd think they wouldn't.
Yes it's old school kit but it still cuts the mustard and most crucially the whole lot - including monitors - stands me a lot less than the cost of a single GTX980!
I may create a "retro thread" or suchlike and put up a few videos showing other games and how they run if there's interest?