Imagine being asked by your readers to grab some 7800 GTX SLI benchmarks at 2048x1536. Sounds fair, given just how fast a pair of the little beggars can be. Still, when it requires you to purchase a new monitor, you know you're either dedicated, or slightly mad.
Luckily, the results of TR's tests lead to more than just a few charts and results. The 7800 GTX seemed to have an exceptional performance advantage over its other high-end brethren. Suspiciously so, in fact. In their quest for answers, TR discovered from ATi and then nVidia that the greatest reason for the performance differential is the size of the Hierarchical Z buffer. HiZ speeds up rendering by ignoring polygons that won't be displayed on screen. However, at uber-high resolutions, the entire frame won't fit into the HiZ buffer, so part of the frame will lack HiZ optimization... unless you're running a 7800 GTX.An interesting read for the polygon heads out there, but don't all go rushing to buy 22" monitors at once - somebody will do their back in.At the end of the day, performance at 2048x1536 isn't really a good indicator of relative rendering power or likely performance in future games, but it is a very interesting special case. For what it's worth, it seems to me that the Radeon X850 XT PE scales up a little more gracefully than the GeForce 6800 Ultra most of the time, although neither card handles uber-res modes as well as the 7800 GTX. The GeForce 6800 Ultra SLI rig, in particular, suffers mightily at three megapixels, so that you're almost better off with a single 7800 GTX.