Overview

You need a fair amount of engineering muscle to jam two of the fastest GPUs you've ever manufactured onto one slab of PCB and still get it running happily, and that's exactly what AMD has done with this, the AMD Radeon HD 6990.

Since the colossal catastrophe that was the initial R600 series of cards from then ATI, the graphics strategy has changed for the boys from Texas.

Starting with the second generation of R600 cards, the HD 3000s, AMD realised that it could no longer keep trying to compete with Nvidia creating the very high-end of graphics chips.

Instead its plan was to create more modular designs that could be at once cheaper and less power hungry than its green-tinted rivals.

The lower-end segment of the graphics card market has always been the area of highest volume. The high-end pixel-pushers though have always been the tech-demos which convince the buying public the rest of the company's lineup has some of their magic in them too.

So whoever had the best top-end GPU could call the shots lower down the pecking order too.

What AMD decided to do to still maintain a presence at the top-table though was to take it's lower-powered GPUs and double them up on a single PCB. That way it could take advantage of multi-GPU CrossFire tech and still sell it as a single graphics card.

And thus the Radeon HD 3870 x2 was born.

AMD wasn't the first to come to market with a single unit, multi-GPU solution, Nvidia had previously released the GeForce 7950GX2. That wasn't quite a single card as it had twin PCBs bound together with an SLI bridge between them, though did plug into a solitary PCIe slot.

Unfortunately it wasn't very good, and Nvidia dropped support soon after launch.

To be fair the Radeon HD 3870x2 wasn't much cop either, but it set a precedent for AMD which has seen its multi-GPU CrossFire performance improve exponentially over the last few years and has laid the foundations for some great cards.

The Radeon HD 4870x2 was one speedy, though baking hot, card and the last generation's Radeon HD 5970 was a landmark card in AMD's history.

The AMD Radeon HD 6990 follows in that tradition taking the top GPU from this current generation, playing around with it a little before fusing a couple onto a single slice of PCB with one hell of a chunky cooler on top to boot.

AMD's focus on multi-GPU as its top end has meant that it's had to drastically improve its CrossFire technology, and now we're at the point where, on a vast percentage of new titles, we're seeing 2x performance increases from that second card.

But are you better off picking up a single card solution such as this AMD Radeon HD 6990 or picking up two of the cards it's based on, the AMD Radeon HD 6970, and building a proper CrossFire rig yourself?

Only one way to find out. Dive in…