Launched in May 14, the Radeon HD 2900 XT is the first of ATI's new Radeon HD 2000 series of desktop graphics cards. Based on the long awaited and long delayed R600 VPU, this makes it the first ATI desktop graphics to support DirectX 10. Like its rivals from NVIDIA, it features a massively parallel unified architecture with general purpose stream processors, instead of dedicated pixel and vertex shaders. Finally a rival on the market for the GeForce 8800 series that have put their stamp on the first months this year, and with full DirectX 10 support for ages. Will the Radeon HD 2900 XT from AMD turn the tables, and up for a challenge against NVIDIA? - Tech ARP

ATI Radeon HD 2900 XT 512MB Graphics Card Review

Compared to its predecessors, it is a massive chip in more ways than one. Packed inside the large chip are 720 million transistors. That's almost twice as many transistors as its predecessors. In fact, it has 39 million more transistors than the NVIDIA G80 GPU used in the GeForce 8800 GTX and Ultra. With that many transistors under the hood, the R600 is not only a big chip, but it is also a hot one. To help keep the size and thermal output of the chip down, the R600 was fabricated on the TSMC 80nm process. Although the smaller and newer 65 nm process was available, ATI chose the 80nm process.

For all those extra transistors, you would have expected the new Radeon HD 2900 XT to offer a tremendous fill rate advantage over its predecessors but that's not the case. The Radeon HD 2900 XT only has a relatively small advantage in texture fill rate over the Radeon X1950 XTX accelerator. Its biggest performance advantage at least in specifications lay not in its processing brawn but rather in its memory bandwidth. Thanks to the super wide 512-bit memory bus, it boasts an incredible memory bandwidth of 105.6 GB/s. And that already beats the GeForce 8800 GTX memory bandwidth.

The Radeon HD 2900 XT makes use of sixteen Hynix 1.0ns GDDR3 memory chips and provide a total capacity of 512MB. These GDDR3 memory chips are designed to run at 2000MHz effective at an elevated operating voltage of 2.2V. At the standard voltage of 1.8V, they are only rated for a clock speed of 1600MHz effective. The Radeon HD 2900 XT is only running these chips at 1650MHz. However, it is not known if ATI is running them at 2.2V or only 1.8V. Therefore, it's hard to say for certain what kind of overclocking potential we are looking at here without actually testing them.

Has the long wait been worth it? Honestly, we don't think so. ATI kept their fans waiting for the Radeon HD 2000 cards, promising better performance than NVIDIA's GeForce 8800 series of graphics cards. However, for all that delay, their new flagship Radeon HD 2900 XT cannot even beat the GeForce 8800 GTX which was released over six months earlier in performance, much less on the GeForce 8800 Ultra. With that said, we have to admit that the Radeon HD 2900 XT is no slouch. While it may not be the killer that ATI claimed it would be, it is still a very, very fast card.

However, power consumption is still prodigious, so much so that ATI had to use a new 8-pin power connector to supplement the first 6-pin power connector. This new connector had many users groaning in frustration as most power supplies only ship with two standard 6-pin power cables. The card will still run at full speed if you just use two 6-pin power cables, but it's advisable for you to switch one of them to a 8-pin power cable to reduce the load on your power cables. The increased power consumption also meant increased thermal output. We are glad to report that ATI has done a pretty good job of it here.

So, it's really a toss-up between the Radeon HD 2900 XT and the GeForce 8800 GTS which is in the same price range. If you have not played any of those Valve games before and are looking for a high-end card that will offer great DirectX 10 performance as well as a convenient High Definition content solution, the Radeon HD 2900 XT is your best choice. Otherwise, the cheaper 320MB version of the GeForce 8800 GTS may still offer a more cost effective solution.