AMD Radeon HD 6990

09.03.2011
I'll be blunt: the AMD Radeon HD 6990 is a beast. Soundly outpacing the best that Nvidia has to offer (at the moment), this dual-GPU juggernaut -- previously codenamed "Antilles" -- clambers to the top of our graphics card heap by serving up the most raw power we've seen to date. But then there's the price: at $699 (as of 3/8/2011), it's strictly aimed at those ultra-enthusiasts who'll spare no expense on their gaming rig.

But rest assured, you're arguably getting your money's worth -- provided you're already living luxuriously on the bleeding edge. The Radeon HD 6990 is pricey, but it proved to be demonstrably faster than its closest competitor, the $500 . For comparison's sake, I also included the $350 -- the company's recent single-GPU speed champ.

The "Cayman" GPU debuted in , in the aforementioned Radeon HD 6970 graphics card. The Radeon HD 6990 combines a pair of these GPUs onto a single card -- think Crossfire, on a stick. The end result is a powerful graphics card that fits comfortably into a single PCI slot (though the card is two slots wide), leaving plenty of room for a second...

In keeping with AMD tradition, the Radeon HD 6990 manages to eke out serious speed while sipping electricity. It's designed to meet a 300W TDP at its stock, factory settings -- that's relatively meager for such a beefy part. The card requires dual 8-pin connectors, so make sure your power supply is up to snuff before you grab your wallet.

The Radeon HD 6990 also offers up something special for customers who want to grind the most power out of their $700 bauble. A dual-BIOS switch on the side of the card toggles the part from its stock, factory-supported position to an overdrive mode, with increased clock speed and voltage demand. AMD calls it the "Antilles Unlocking Switch for Uber Mode," or AUSUM; I won't. Coupled with AMD's Power Tune application, you'll have a wide range of control over the GPU and Memory clocks. For these tests, I also compared the Radeon HD 6990 at its stock speeds (830 MHz), to it's base overclocked setting (880 MHz) -- referred to as Radeon HD 6990 OC for simplicity's sake.