Race Driver: GRID is the newest game in our testing arsenal and it's currently one of our favourites too. Its combination of arcade style thrills and spills with a healthy dose of realism and extras like Flashback makes it a great pick-up-and-go driving game. It's also visually stunning with beautifully rendered settings, interactive crowds, destructible environments, and stunning lighting. All that and it's not the most demanding game on hardware, either.
We test using the 32-bit version of the game, which is unpatched and running in DirectX 10 mode. FRAPS is used to record frame rates while we manually complete one circuit of the Okutama Grand Circuit, in a Pro Tuned race on normal difficulty. We find a frame rate of at least 40fps is required to play this game satisfactorily as significant stutters can ruin your timing and precision. We'd also consider 4xAA as a minimum as the track, barriers, and car bodies suffer considerably from aliasing and are a constant distraction.
All in-game settings are set to their maximum and we test with 0xAA, 4xAA, and 8xAA. Transparency anti-aliasing is also manually turned on through the driver, though this is obviously only enabled when normal AA is being used in-game.
The HD 4870 X2's poor result for 2,560 x 1,600, 8 x AA is something we've seen a few times before with this game. When detail settings and resolutions are pushed beyond a certain point, performance just plummets. The point at which this happens is different for every card but it consistently rears its head. What we've found, though, is that tweaking things just a little will bring that performance right back to where it should be so while you may not be able to get conventional 8xMSAA you may be able to use one of ATI's Custom sampling filters and get much better performance.
As for overall performance, the HD 4870 X2 holds up very well. Although this game remains playable with most of the cards on test, the HD 4870 X2 manages to pull away at the most extreme settings, sometimes even doubling the performance of the GTX 280.