With version 10.0 of Microsoft's DirectX programming interface arriving early next year, we can't expect graphics card manufacturers to make radical revisions just now. It's unsurprising, therefore, that ATI's Radeon X1950 XTX chip has a large number of similarities to its predecessor, the X1900 XTX. However, ATI has also found room for a few novel features and specifications you won't have seen before – and we reckon these make it the best-value true high-performance card on the market.

Arguably the most notable of these is the presence of GDDR4 (graphics double data rate, fourth generation) RAM. ATI was instrumental in bringing GDDR3 to the market, and it's played a similar role here.

The new GDDR4 RAM combines a lower voltage requirement with a fixed burst length that's twice as high as that of GDDR3. In essence, this means the memory needs much less power to run at the same clock speed, and can therefore be run faster.

Whereas the Radeon X1900 XTX had a memory core speed of 775MHz (1.55GHz with DDR RAM), the X1950 XTX can run its memory at a massive 1GHz (2GHz with DDR RAM). As a consequence, the memory bandwidth jumps from 49.6GBps (gigabytes per second) to 64GBps. Not only is this a huge step forward from the older Radeon X1900 XTX, but it's also significantly ahead of the 51.2GBps of nVidia's GeForce 7900 GTX, giving the Radeon X1950 a clear advantage over its main competitors.

Pixel shaders

In other respects, though, the X1950 XTX differs very little from the X1900 XTX. Generally this is no bad thing, because that card's 48 pixel shader processors already significantly outnumbered those in the nVidia cards. Should games programmers ever start to write their code to take full advantage of pixel shader processors, the X1950 XTX will find itself in the driving seat.

The core clock speed is identical to the X1900 XTX, and both cards are built using the same manufacturing process. The cooling solution has been revamped from previous ATI designs, however, and the X1950 XTX is incredibly quiet considering its astonishing power.

In terms of performance, the X1950 XTX falls behind the GeForce 7950 GX2. However, that card has two graphics chips rather than one, and costs almost half as much again as the X1950 XTX. The XTX should come in at a similar price to the GeForce 7900 GTX, which is bad news for the nVidia chip, since the Radeon proved to be faster – particularly at higher resolutions (1,600x1,200) and with full detail bolted on.

At 1,280x1,024, the cards are fairly similar. Even so, given the potential of the pixel shaders, we'd say the X1950 XTX was the better deal overall.

ATI's new batch of graphics cards

Graphics chip makers have a habit of never releasing one product when they could chuck out four or five. This time is no exception, so here's a quick taste of what else you can expect to see canter out of the ATI stable in the next month or so.

Starting with the cheapest first, we have the X1300 XT. Or, rather, we have the X1600 Pro masquerading as an entirely new card. Devious this tactic may be, but it's good for the customer, since the X1600 Pro remains a fairly decent little model. And now you can buy it for £60 to £70, which makes it about a tenner cheaper than it used to be. Given the presence of 12 pixel-shader processors and a core clock running at 500MHz, this will remain a very interesting budget option.

The X1650 provides rather more clout. It offers slightly improved performance (thanks to the extra 10MHz upgrades to the core and memory clock speeds) over the X1600 XT, and should retail for £85 to £90 (around £5 more than the XT).

Finally, a 256MB version of the X1900 XT is going to be released. Aside from the reduced memory, the specifications should be identical to those of the 512MB version. It remains to be seen exactly what (if any) effect the 256MB will have on games titles, but since these new cards are likely to cost just £180 to £190, it should prove an interesting product. Those who want high framerates but don’t want to pay more than £200 will be particularly intrigued, we suspect.

Sapphire Radeon X1950 XTX: Specs

  • ATI Radeon X1950 XTX graphics processor
  • 512MB DDR4 RAM
  • core clock 650MHz
  • memory clock 1GHz (2GHz DDR effective)
  • manufacturing process 0.09-micron
  • 48 pixel shader processors
  • 256bit memory interface
  • PCI Express interface
  • DirectX 9.0 support
  • DVI
  • video-out
  • ATI Radeon X1950 XTX graphics processor
  • 512MB DDR4 RAM
  • core clock 650MHz
  • memory clock 1GHz (2GHz DDR effective)
  • manufacturing process 0.09-micron
  • 48 pixel shader processors
  • 256bit memory interface
  • PCI Express interface
  • DirectX 9.0 support
  • DVI
  • video-out

OUR VERDICT

We'll have to wait until next year for the really juicy developments in graphics card technology. But for now, the Radeon X1950 XTX's improved memory bandwidth is enough to secure it a comfortable victory over the GeForce 7900 GTX. If £310 is your budget for a graphics card, this is clearly the one to have.

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