The most expensive card in ATI's range is the gigantic Radeon HD 4870 X2. It's a pair of HD 4870 GPUs crammed onto a single PCB.
The list of specifications is quite awe-inspiring: 750MHz core clock speeds, 1600 stream processors and 956 million transistors for each of the two GPUs. You can also choose from either one or two gigabytes of HD 4870-exclusive GDDR5 memory - go for the latter and a 64-bit OS is essential, though.
At high resolutions and quality settings, the HD 4870 X2 is the fastest graphics card in the world. It wasn't as quick as the GeForce 9800 GX2 in our less arduous Crysis tests, but pulled ahead in our very high quality test at 1920 x 1200, with 35fps to the 9800 GX2's 28fps.
Other tests echoed this performance - the 4870 X2 was the only card that managed to maintain a playable frame rate in our most demanding Call of Juarez benchmark. Far Cry 2 provided little resistance, either, with the X2 proving quicker than the 9800 GX2 - 139fps compared to 105fps.
Of course, this card does have caveats. It's a huge, heavy and reasonably loud card that weighs 1.1kg and is almost a foot long. In these credit crunch afflicted times, spending $747 on a graphics card may seem more than a little frivolous too.
If you're determined to game at the highest quality settings and resolutions, though - and have the power supply, chassis and wallet to handle it - then this is the fastest graphics card money can buy.