Packed with just over 300 million transistors, nVidia's latest high-end graphics chip, the GeForce 7800 GTX, is one of the most complex processors ever designed.

And tests of a reference board built around the chip indicate that it's the fastest graphics board we've ever seen.

NVidia expects boards to ship now from partners such as Asus and Chaintek at a retail price of around £400. We tested a single-slot PCI Express board equipped with 256MB of 600-MHz DDR3 memory and dual DVI (digital visual interface) outputs.

The board set speed records in almost all gaming tests – an impressive feat. For example, in a Doom 3 test with anti-aliasing, the 7800 GTX posted frame rates of 65 and 42fps (frames per second), respectively, at 1,024x768 and 1,600x1,200 resolution. By contrast, a previous speed leader, ATI's Radeon 850 XT Platinum Edition, managed only 52 and 31fps, respectively, in the same tests.

In addition, the 7800 GTX supports nVidia's SLI technology. This allows you to run two identical graphics boards in a system built to permit such doubling up, dramatically boosting performance in some games.

The GeForce 7800 GTX is priced out of the range of all but the most well-heeled gamers, although our tests demonstrated that it delivers pretty good value. That nVidia managed to fit everything into a single-slot board cooled by a reasonably quiet fan is doubly impressive.