While architecturally it's difficult to compare Nvidia and ATI cards, there are a few clear feature differences. For a start, there's the lack of support for PhysX in ATI's cards. This is the physics simulation engine used on a number of modern games, with Mirror's Edge being a particularly well-known example. In the long run, there is likely to be a transition to using open standards for physics calculations, and certainly not every game uses the tech, but for the time being you do miss out on this feature.
Also, Nvidia supports 3D gaming on its cards, though frankly we don't see this as much of a value-add yet, especially as you need special high-speed monitors and the glasses to take advantage of it. Finally, the GTX 400 series are the first graphics cards able to apply antialiasing to foliage in Crysis. A minor point, perhaps, but if you want the best visual quality in that game, it's worth considering.
So that's this card's features but of course the all important part is performance and here the Zotac GeForce GTX 480 holds up pretty well. Starting with our DirectX9 and DirectX10 games tests, it clearly takes a monumental leap forward in performance over its predecessor the GTX 285 and mostly beats the GTX 295. However, while it still holds a lead over ATI's HD 5870, it's not nearly as significant a one and the HD 5970 comfortably takes the overall crown.
When it comes to DirectX 11 titles, the GTX 480 holds a strong lead over the HD 5870 in two out of the three tested titles but falls comfortably behind in Just Cause 2. Overall we expect the GTX 480 to come out on top on average against its single-chip counterparts as more DirectX 11 titles come out, though. However, when it comes to out and out performance the ATI HD 5970 is way ahead of all the other cards on test. Even considering our concerns mentioned earlier, it's hard to ignore just how fast this card is.
This ignores cost, though, which makes the HD 5970 look like a less attractive proposition. Purely on a value level it's not much worse than the GTX 480, but £550 is just an insane amount of money to spend on a single graphics card. Moreover, when the HD 5870 costs just £350, neither of these cards seems like good value. Indeed, that's the key point about the GTX 480: yes, it's the fastest single-chip card on the planet but it's not £100 faster than the HD 5870 and for most gamers with a single screen it's just overkill.
The Zotac GeForce GTX 480 is the fastest single-chip graphics card on the planet; that much is clear. Arguably it also holds an advantage when it comes to features, thanks to PhysX support amongst other things. However, when it comes to value it simply doesn't deliver. Add in that it runs extremely hot and noisy and sucks up loads of power and we can think of few reasons to recommend it over the cheaper alternatives from ATI.