Unless you're an avid gamer, you've probably missed the fact that Nvidia currently finds itself in something of a unique position.

Its G80 family is the only one to offer support for Microsoft's DirectX 10, and the 8800GTX holds the title of the single fastest card currently available too. It's rare that one chipmaker can hold such a lead, and the release of ATI's latest GPU doesn't change the landscape quite as much as expected.

Looking purely at the specification and its heritage, the ATI Radeon HD 2900 XT has strong potential. Described by ATI as its second generation unified shader architecture (the main requirement for DirectX 10), its origins can be traced back to the graphics brains of the Xbox 360, aka Xenos.

There are 320 stream processors inside the core, arranged as 5-way shader processors, effectively giving you 64 shader units that can handle vertex, pixel and geometry operations.

The memory bandwidth is fundamental to the performance of modern graphics chips, and the chip previously known as R600 has lifted the bar yet again.

The 512-bit ring memory bus offers a peak throughput of 106GB/s, which is faster than any other card out there - impressive as it uses existing graphics memory. These initial cards pack 512MB of GDDR3 memory, clocked at 828MHz, with the graphics core clocked at an equally non-standard 740MHz.

These are strong figures for a modern graphics card, but there are some details that do lag behind the current performance leader.

This core has only half the texture units of the 8800GTX, and only 16 ROPs (Raster Operations) as opposed to the GTX's 24. So despite the huge memory bandwidth, it still trails the GTX noticeably. 3DMark06 and indeed most of the games we tested put this card more on a par with the 8800GTS 640MB, which costs roughly the same.

HD streaming

This card isn't just about games though. ATI has included a Universal Video Decoder, which takes the load of handling the bitstream for HD content off the processor and handles it in the graphics card.

In testing we saw processor usage more regularly in the ten per cent bracket as opposed to 40 per cent, even with H.264 material. The fact it has an audio pass through to the HDMI connector makes this a particularly tempting card for playback, although there will be more affordable versions of this GPU available later in the year.