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Performance
This is it isn't it? This is what you want to know, how does this frankly enormous graphics card perform in-game.
The short, obvious, answer is very well indeed.
It's obvious because we've already tested how quick two of these GPUs paired up can be by CrossFiring both the AMD Radeon HD 6950 and AMD Radeon HD 6970.
So it will come as no surprise to learn that there really isn't any single graphics card yet capable of coming close to giving the Radeon HD 6990 a real run for its money. As you can see from the benchmarks Nvidia's current top-end card, the GeForce GTX 580, is quite a way off the pace of this twin-GPU setup.
That's not a great surprise considering the single GPU Fermi card has less than half the graphics memory and half as many chips flinging the pixels around. But then it's also £150 less than this pricey ol' card.
The key thing to take away from the Radeon HD 6990's performance at it's stock settings is that, while it consistently outperforms the Radeon HD 6950 in CrossFire, it comes up short against the higher clocks of the standard HD 6970s when paired up.
This is why AMD has dropped in the added extra of the Antilles Unlocking Switch.
That puts its clock speeds to match the HD 6970. When this 'hardware Overdrive' BIOS is used the performance numbers jump up that little bit extra to sit almost exactly where a CrossFire HD 6970 setup does.
The overclocked speed of this Radeon HD 6990 then puts it that little bit ahead of the previous generations of AMD multi-GPU cards. Those cards couldn't get by running their GPUs at the same clock speeds as the fastest chips of their respective generations, whereas this can.
Granted with all this graphical prowess, and four of AMD's tessellation engines working in unison, we still can't beat 30fps in our Metro 2033 benchmark at the top resolution, but we are getting close.
And it's at that 2560x1600, 30-inch panel, resolution that the HD 6990 needs to be tested. After all there's little point pairing such a graphics processing behemoth with a weedy 1080P monitor, you're just not getting the most from your £550-odd outlay.
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