If you're in the market for a new gaming graphics card then you may well be considering an ATi X1800, in which case hold your horses: ATi has just launched the X1900, which powers this new card from Sapphire.

Visually there is no difference between an X1800 graphics card and an X1900; they're big double-slot cards with a copper cooler on the graphics chip which is cooled by a 65mm fan that sucks air from inside the case and expels it through vents in the bracket.

The cooling system is terribly noisy as the air rushes through a restrictive duct, and when the fan spins up to a full 5,100rpm at start-up it is horrendously loud. The fan then slows down to 1,800rpm when the drivers take control.

You may expect that X1900 is simply a speed revision of X1800 but in fact ATi has made some significant internal changes, such that each of the 16 pixel pipelines now has three pixel shaders to give a total of 48 shaders, where X1800 had 16 pipelines and 16 shaders. This has raised the transistor count from 321 million to 384 million, as ATi has retained all of the other X1800 features such as the twin 256-bit ring memory controller and the Avivo video decoding hardware.

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The GeCube RX X1800XTD which we are using for comparison has a core speed of 620MHz and memory that runs at an effective speed of 1.5GHz, which is slightly faster than the Sapphire Radeon X1900 XT which has speeds of 620MHz/1.45GHz. The changes to the pixel shaders put the emphasis squarely on Shader Model 3 image quality, so perversely you may find that an X1900 is no faster than an X1800 unless you are stressing the Shader Model 3 features in a new game.

We tested both the Sapphire Radeon X1900 XT and the XTX which are identical apart from their speeds and prices. The package of cables and adapters is full and comprehensive and you also get a decent selection of software in the shape of PowerDirector 4DE and PowerDVD 6 Stereo.

Added to that Sapphire includes its Select games package. This is a DVD with Tony Hawks Underground 2, Richard Burns Rally, Prince of Persia Warrior Within and Brothers in Arms Road to Hill 30. You can try all four games for an hour and then select one as a free installation. Neat idea, but the games aren't exactly new and current.

The XT is clocked at 620MHz/1.45GHz and costs £411 while the XTX runs at 650MHz/1.55GHz and costs £469. In both cases the ATi drivers can overclock the memory to 1.6GHz while the XT core can reach 650MHz, which makes it an honorary XTX. The XTX can go as high as 690MHz but there's a note of caution as our overclocked XTX overheated during an intense session of F.E.A.R. and locked up.

There's another concern with the XTX as ATi will release the CrossFire version any day now which will run at the XT speeds, so if you hook up an XTX in CrossFire you can expect it to drop its speeds to those of an XT.

Taking all that together we reckon that the XTX is a bit of an exercise in Public Relations, and you should concentrate on the XT. It's a formidable piece of hardware that has the performance edge on a 7800GTX, although no doubt Nvidia will redress that with the GeForce 7900 Ultra in March.

There's little point in talking about value for money as every high-end gaming graphics card since the dawn of time has cost a fortune, and nothing changes here. £411 is a lot of cash for the Radeon X1900 XT, but Sapphire delivers plenty in return.

We like the Sapphire Radeon X1900 XT a great deal, in preference to the more expensive XTX, and we don't want to give it back for a month or two. Would we buy it? No of course not (see above comments about value for money) but we were very, very impressed.