Editor's note: When this review was first published, the Half-Life 2: Lost Coast demo chart was labeled simply Half-Life 2. The Lost Coast demo implements more-advanced 3D features than the original Half-Life 2 graphics engine. We've come to terms with the modern high-end 3D card occupying one slot while blocking an additional expansion slot, so we'll stop complaining about it. We'll merely state as fact that the Radeon X1900 XTX is bulky due to the large fan and cooling assembly; it occupies one x16 PCI Express lot, while blocking access to the x1 or x4 PCI Express slot next to it. We've also accepted that most 3D cards now require a direct connection to your PC power supply. A single Radeon 1900 XTX requires a 450-watt power supply, while a CrossFire configuration needs at least a 550-watt power supply (and ATI recommends "38 amps on the 12-volt rail;" check your PSU's specs to see if yours fits the bill). If you're building a high-end PC, you should know by now that it will require lots of power. These specs are no different than those required by comparable Nvidia configurations. It's best to accept it, do research, acquire the power supply you need (which will vary based on the CPU and other hardware in your system), and move on.
Internally, the Radeon X1900 XTX leaps ahead of its predecessor, the Radeon X1800 XT. The core clock and memory speeds on the X1900 XTX receive a nominal boost to 650MHz and 1.55GHz, respectively--up from 625MHz and 1.5GHz on the X1800 XT. That might not seem like much, but the newer card also uses faster 775MHz memory to the older one's 750MHz. In a more significant change, ATI tripled the pixel shader pipelines. The Radeon X1900 XTX has 48 lanes for processing surface details, up from the 16 on the X1800 XT and twice as many as the 24 on the GeForce 7900 GTX. That means either faster performance or more detail, depending on how much and what kind of information you throw at the card.
ATI's entire X1000 series maintains an advantage over Nvidia's GeForce cards in that they can perform some advanced graphics-quality tricks simultaneously that Nvidia's cards can do only one at a time. The problem is, they're mostly theoretical. In the few games that feature high dynamic range lighting (that is, extreme shadows and extreme lighting that shines with accurate cloudiness from its source), ATI's cards let you enable that feature and antialiasing (removes the jaggedness from diagonal 3D lines) at the same time. The Elder Scrolls IV: Oblivion is one game where you can do it (by way of an unofficial driver update called the "Chuck patch"), and there are a handful of others. GeForce cards can only do one or the other at a time. In recent history, ATI's cards have traditionally fared well in single-card tests when compared to their Nvidia equivalents, and the Radeon X1900 XTX is no different when matched up against the GeForce 7900 GTX. Our F.E.A.R. test is the most telling in our 3D suite because it's the most demanding DirectX-based game, which is a much more common design language, or API, than the Doom 3 engine's Open GL. And in single-card mode, at least, the Radeon X1900 XTX beat the GeForce 7900 GTX at every resolution, although by only a small margin.
(Longer bars indicate better performance)
|1,280 x 960||1,600 x1,200||2,048 x 1536|
In CrossFire mode, however, the Radeon X1900 XTX is a hard sell. It manages to win at Half-Life 2: Lost Coast demo at the more common 1,280x1,024 and 1,600x1,200 resolutions, but as the pixel count gets to 2,048x1,536, the Radeon cards fall behind a pair of GeForce 7900 GTX cards in SLI mode. And while it still looks great, the Half-Life 2 engine is beginning to show its age. As we stated, F.E.A.R. is perhaps the best current indicator of next-gen performance, and on that test, the Radeon X1900 XTX in CrossFire mode lags behind the 7900 GTX's dramatically at both 1,280x960 and at 1,600x1,200. It closes the gap at 2,048x1,536, but success at that rarely used resolution is not enough to elevate it to common superiority.