It should be, but there are a couple factors that can change this. What brand is it? How many Amps on the 12V rail(s)? Do you already own it or are you in the market for one?
To personally answer these questions, I would start at looking at some brands like Corsair, PC Power and Cooling, Antec, even Cooler Master and Thermaltake make nice units.
When I refer to Amps, that is mostly for the health of your GPU and PSU over time, you defiantly do not want to starve the GPU or push the PSU too far. I would feel safe with recommending a PSU with at least 36 Amps on the rail(s) to give you ample head room. (Considering I would guess that you are talking about a GTX 560 Ti)
And if you do have said PSU already, please post some of the specs on the side of the unit so that we can give you more advise. I hope this helps, and happy building!