Sapphire Radeon HD 5850 graphics card

The Radeon HD 5870 first showed us the joys of ATI's DirectX 11.0 technology, but it was the 5850 that shoe-horned it into a package that offered real value for the fervent gamer.

Both graphics chips are manufactured using the 40nm process. The 5850 is a little shorter than the 5870, but it also runs cooler and consumes less power at 151W under maximum load. It requires a pair of six-pin power connectors. You get both HDMI and DVI ports, and the 5850 can support up to three screens. Eyefinity adds the ability to stretch some games across those three displays.

The basic architecture is based on a 256bit memory interface. The specifications have been trimmed slightly, so the 5870’s 850MHz core clock becomes 725MHz in the 5850. The memory clock speed has been turned down from 1.2GHz to 1GHz, and the number of stream processors is sliced from 1,600 to a still impressive 1,440. All this should give the 5850 the edge over both the GTX 470 and 480. Its floating point of 2.09TFlops is almost twice that of the GTX 470’s 1.09TFlops, while the fill rate sees it beat even the GTX 480 by more than 10.2GTps. This is due to a generous sampling of texture units.

But superiority on paper doesn’t always result in a commanding lead in real-world performance. The 5850 is a slower card than the GTX 470, but the difference wasn’t as great as the $100 price gap might suggest. In Hawx, it trailed by around 8 to 12fps, but in Aliens vs Predator the difference was less than 2fps as detail levels were raised. Our Crysis tests occasionally saw the 5850 beat its rival.

Of the $350-plus cards we've tested recently, the 5850 saw the greatest drop in performance when moving from DirectX 10.x to 11.0. We suspect this card will have few problems with future DirectX 11.0 games, however.

The 5850 is slower than the GTX 470 in most tests. But it costs less and runs cooler and quieter.