ATI CrossFire - Hands on

We've already said we're not going to go all out to measure performance, since the hardware we have is reference ATI kit and we believe there are still driver revisions to come. However, these numbers should give you an indication of performance.

We compared X850 CrossFire cards to 6800 Ultras. We have not compared them to 7800 GTs or GTXs. We know that next-generation cards are in a class of their own. It's more interesting to see how CrossFire scales compared to SLI from a single card set up. Rest assured that we'll bring you a full comparison with GeForce 7800 when Radeon X1800 launches.

For our NVIDIA test rig, we used an AMD Athlon FX57, 1GB Crucial Ballistix RAM, two Point of View 6800 Ultras, seated on a MSI K8N Neo Platinum board.

For our ATI test rig, we used the Evesham system consisting of an AMD Athlon FX57, 1GB Hynix RAM, the ATI reference X850 XT Master card and Slave cards, and the reference CrossFire motherboard.

A big 'Thanks!' to the guys at Gladiator Computers for the 6800 Ultras.

Splinter Cell: Chaos Theory

We used the Lighthouse timedemo for this test. We turned on all the eye candy (Tone mapping, Parallax mapping, HDR) as well as 8x Anisotropic filtering, using patch 1.04 which supports those features on ATI cards. We tested at 1024x768. (Note there's no AA, because SC:CT doesn't support AA and HDR simultaneously).

So, a few things we can see here. One is that the ATI system is much faster than the NVIDIA system; based on our previous experience of the X850 XT, it looks like the CrossFire motherboard is very fast, with a wider performance differential than we've seen previously from comparing the X850 XT to a 6800 Ultra. The other is that the gain for CrossFire over single card is around the same as the gain for SLI over a single card. A single X850 XT provides 54% of the performance of a CrossFire rig, whereas the single 6800 Ultra is 55% of the SLI performance.

Doom 3

We used Timedemo 1 for this test, at 1024x768 with 4xAA and 8xAF and all details set to high.

CrossFire is again, faster here. There's a 25% performance gain for CrossFire, and a 30% gain for SLI.

The Bottom Line

The net result? CrossFire works, and it works pretty darned well, from our initial observations.