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Fresh competition
Nvidia hasn't been sitting still as AMD has released its new products. Fortunately, this review gives us a chance to catch up on some new developments from the GeForce folks, as well. Among them is this EVGA GeForce 8800 GTS "Superclocked" card:

We took a brief look at this card in our initial Radeon HD 2900 XT review, and we said we'd follow up later. Now is the time. This card has a 575MHz core clock and 1.7GHz memory, a nice boost from "stock" GTS speeds. Of course, it's fully warranted at these clock speeds. At $394 at Newegg, this is tough new competition for the GDDR3 version of the 2900 XT.


These monsters are GeForce 8800 Ultra cards from XFX. We were underwhelmed by the Ultra when it was introduced because it didn't offer much of a speed boost over the 8800 GTX, yet it cost quite a bit more. We said at the time that higher-clocked versions of the card might bring some redemption for the Ultra and pledged to keep an eye on it. Well, here you have the GeForce 8800 Ultra "XXX" from XFX, clocked at a stratospheric 675MHz, with 2.3GHz memory and a 1667MHz shader core. Now that's a little more like it. Furthermore, the price of even this stupid fast Ultra is down to $699.99 at ZipZoomFly. It ain't cheap, but it's certainly not the heart-stopping $830 price tag attached to Ultras at their launch, either. Perhaps a measure of redemption for the Ultra is, ahem, in the cards?

The matchup
Before we dive into our test results, let's pause to have a look at the theoretical matchups between these cards.

Peak
pixel
fill rate
(Gpixels/s)
Peak texel
filtering
rate
(Gtexels/s)
Peak
memory
bandwidth
(GB/s)
Peak
shader
throughput
(MFLOPS)
GeForce 8800 GTS 10.0 12.0 64.0 346
EVGA GeForce 8800 GTS Superclocked 11.5 13.8 68.0 389
GeForce 8800 GTX 13.8 18.4 86.5 518
GeForce 8800 Ultra 14.7 19.6 103.7 576
XFX GeForce 8800 Ultra XXX 16.2 21.6 110.4 640
Radeon HD 2900 XT 11.9 11.9 105.6 475
Radeon HD 2900 XT 1GB GDDR4 11.9 11.9 128.0 475
Radeon HD 2900 XT 1GB GDDR4 OC 13.2 13.2 134.4 528

I don't want to dwell too long on these numbers, because they're just theoretical peaks, but such things do tend to matter in graphics. The big things to take away from this table are pretty obvious. The GeForce 8800 cards tend to beat out the Radeon HD 2900 XT cards in texture filtering rate—in some cases, like the 2900 XT 1GB GDDR4 vs. the 8800 GTX, by quite a bit. The GeForce 8800 is simply loaded on this front. Conversely, the various flavors of the Radeon HD 2900 XT tend to have vastly more memory bandwidth than the competition, as we've already noted.

Peak shader throughput is a tricky thing, but I'll give you my take. The numbers above give Nvidia's G80 GPU credit for a MUL instruction that it can co-issue in certain situations. If you take that away, which might be the more realistic thing to do, the G80's numbers above would be reduced by a third. I think the peak numbers we have listed for the R600 are a little more solid, but this GPU's real-world performance may be impaired by the superscalar nature of its execution units. Scheduling instructions optimally on such a machine can be challenging. The G80's scalar architecture is more naturally efficient. My sense is that the R600 has more peak raw shader power, but that may not matter much in the end.

Now, let's have a look at performance.