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Up to this point I've talked little about the technology that powers the two graphics chips sitting at the heart of the 9800 GX2 but this is for one very good reason. There's actually very little in the way of new features. The chips are based on the same G92 cores that power the 8800 GT and 8800 GTS 512, which in turn are based on the same basic architecture that powered the 8800GTX. So, if you want to bone up on the details of how these chips go about doing their graphics processing business we suggest you give those articles a read.
In a nutshell, on each chip you get 128 stream processors (split into eight shader clusters) running at 1,500MHz. Each shader cluster then has eight texture addressing and eight texture filtering units. These run at the core clock frequency of 600MHz, along with the 16 render backends, or ROPs. Each chip is then accompanied by a hefty 512MB chunk of memory, which runs at 1,000MHz (effectively 2,000MHz) and communicates over a 256-bit memory channel.
If all that went straight over your head, think of it like this; the 9800 GX2 is two 9800 GTX cards strapped together. When you combine the power of the two cards, you theoretically get 768 GigaFLOPS of shader processing power, a texture fillrate of 76.8 Gigatexels per second, and pixel fillrate of 19.2 Gigapixels per second. These are undeniably impressive figures but of course harnessing that power requires game and driver support to be top notch and this is certainly something that's difficult to guarantee. However, what we can do is tell you how it performs with the games we have at our disposal. So without further ado, let's look at the numbers.
* Intel Core 2 Quad QX9770
* Asus P5E3
* 2GB Corsair TWIN3X2048-1333C9 DDR3
* 150GB Western Digital Raptor
* Microsoft Windows Vista Home Premium 32-bit
* nVidia: forceware 175.16
* ATI: Catalyst 8.4
Due to some problems with our test bed (we think the hard drive was corrupting things) we weren't able to test as many games as we did when we looked at the HD 3870 X2 so we can't say quite so comprehensively what compatibility is like with this card. However, in the games we did test it's pretty clear from our results that the 9800 GX2 is indeed the fastest card on the planet. All except in our Counter-Strike: Source test, which obviously wasn't taking any advantage of SLI - no doubt due to our offline version of the game being slightly out of date. Bearing this in mind, and the fact that some of our other games (in particular Crysis) didn't work, we will certainly be retesting sometime soon and updating this article accordingly.
In the mean time though, it's clear that if money is no object then this is certainly the card to go for. Yes, power consumption is quite high but then you can take advantage of HybridPower to run things more efficiently. Also, buying two 8800 GTS 512 cards and running them in SLI will get you similar performance and save £50 but then you're limited to a large SLI motherboard. Finally, while compatibility may be a problem, even if SLI isn't supported properly, just one of the internal cards will still give impressive performance in most of today's games. Indeed what the 9800 GX2 does is, once again, highlight how graphics hardware is waiting for games to catch up, rather than vice versa. With the exception of Crysis, and unless you run games at the absolute highest resolutions, any card over £200 will serve you just fine.
nVidia's GeForce 9800 GX2 is undeniably a superbly fast card if and when it works. The only real kicker is the price, which is understandably high. Still, if you've got a few hundred pounds burning a hole in your virtual pocket then we'd recommend it.