Verdict: The 7900 GS and GT have had their day, but the 7900 GTX.

Much like the 7800-series, Nvidia's GeForce 7900 GT and 7900 GTX are no longer available to buy in the shops. This time last year, the 7900 GT was the second most powerful high-end Nvidia-based graphics card, costing a tidy £260. However, with the advent of DirectX 10 graphics cards, its glory days as a high-end card are now long gone. While you're unlikely to see any GeForce 7900 GT cards on the shelves, the card's spirit lives on in the form of the GeForce 7900 GS. Released in September last year, the 7900 GS was Nvidia's attempt at revamping the series, creating a more competitively priced mid-range card.

In an effort to reduce manufacturing costs, the 7900 GS is leaner than the 7900 GT. As our tests show, however, the 7900 GS performs almost identically to the 7900 GT in every game, despite having only 20 pixel processors, four fewer than the 7900 GT, and seven vertex pipes, as opposed to the eight in the 7900 GT.

This isn't too surprising, since the cards are identical in all other aspects. The 7900 GS has a GPU clock speed of 450MHz, and is paired with 256MB of GDDR3 memory clocked at 660MHz (1.32GHz effective). Much like the 7900 GT and 7900 GTX, the 7900 GS is built on the same 90nm fabrication process that's used for all the latest Nvidia cards, and sports a healthy 256-bit memory interface. The 7900 GS also boasts 16 ROPs, double the amount of the 7600 GT. All this gives Nvidia enough confidence to send the 7900 GS out fighting with a mid-range £95 price tag round its neck.

In F.E.A.R., the 7900 GS put up an impressive showing for such a cheap card, managing to provide a playable frame rate at 1,680 x 1,050 with 2x AA and 8x AF, the native resolution of a 20in or 22in widescreen TFT. However, in more modern games, the 7900 GS started to show its age. Need for Speed: Carbon returned a minimum frame rate of just 20fps at the low resolution of 1,024 x 768, which is just too slow to be playable. S.T.A.L.K.E.R. was even more disappointing, since first-person shooters require a perfectly smooth frame rate to provide accurate movement, and the 7900 GS didn't have enough grunt to keep the frame rate above 25fps at 1,024 x 768, even without any AA or AF.

The 7900 GS's main DirectX 9 foe is the similarly priced Radeon X1950 Pro, and the ATi card is a much better performer in Need for Speed: Carbon, managing to provide a playable frame rate at 1,280 x 1,024 with 2x AA and AF enabled. The ATi card also significantly outpaces the 7900 GS in F.E.A.R., although it's just as poor as the 7900 GS in S.T.A.L.K.E.R.

The strong performance of the X1950 Pro means that, if you have £100 and are looking to buy a new card, you should cross the 7900 GS off your shortlist. With the performance of Nvidia's new mid-range 8600 GT and 8600 GTS cards also being distinctly unimpressive at the moment, the X1950 Pro offers the highest return for your money, at least in DirectX 9 games. If you already own a 7900 GS, however, the next obvious step up is a 320MB GeForce 8800 GTS, although if you can find a Radeon X1950XT for the right price, this is also worth considering.

For owners of a 7900 GTX, the picture is a little rosier. The 7900 GTX may have the same architecture as the 7900 GT (24 pixel processors, 24 texture processors and 16 ROPs), but its GPU has been clocked much higher - 650MHz as opposed to 450MHz.

The GTX has also been endowed with faster 800MHz (1.6GHz effective) GDDR3 memory, as opposed to the 660MHz (1.32GHz effective ) RAM of the 7900 GT and GS. This extra grunt means that the 7900 GTX has aged gracefully.

Most notably, it's able to play F.E.A.R. smoothly at 1,680 x 1,050 with 2x AA and 8x AF, and can handle new games such as S.T.A.L.K.E.R. at 1,280 x 1,024 with AA and AF enabled.

While a GeForce 8800 GTS would be a beneficial upgrade for 7900 GTX owners, if you don't mind playing new games at modest resolutions then an upgrade isn't necessary until DirectX 10 games become more commonplace.

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