Conclusion

Flawless CrossFire

Now that we have tested the new incarnation of ATI CrossFire technology we can state that it has matured and has completely got rid of the deficiencies of the original CrossFire.

Most important is that the display mode limitations have been removed. Resolutions over 1600x1200 could not be used previously, but now the ceiling is as high as 2560x1600 at 60Hz. That’s an exotic mode indeed, but as for the popular resolutions like 1600x1200, you can now use them at higher refresh rate frequencies, comfortable and safe for your eyes. ATI’s solution of the problem – they installed two TMDS receivers and two TMDS transmitters – may not seem very elegant and certainly makes the Master card more complex, but it works all the same.

Taking a very critical approach we could still find at one disadvantage in the new CrossFire: using an external RAMDAC and lacking a TV encoder chip, this graphics subsystem cannot output to devices with composite or S-Video input. On the other hand, these video interfaces do not provide the best image quality possible and do not match the high-end product class the RADEON X1800 XT CrossFire platform belongs to, so it can hardly be considered a serious drawback. We guess people who can pay the price of this platform have already got modern TV-sets with DVI or HDMI inputs.

Like the RADEON X850 XT CrossFire Edition, the RADEON X1800 XT CrossFire Edition gives you some flexibility in configuring your multi-GPU system. Particularly, it can make up a pair not only with another RADEON X1800 XT but also with a less powerful RADEON X1800 XL. Of course, half the memory won’t be used then and you need to reboot the system to turn on the CrossFire mode. The efficiency of such a configuration would be low due to the big discrepancy in the clock rates of the two cards, yet you can really unite a RADEON X1800 XT with a RADEON X1800 XL and this will work. This option may be interesting to owners of a RADEON X1800 XL.

CrossFire Works – And Works Well

The previously reported compatibility problems have vanished, too:

It’s only in one game, in the 3D shooter Project: Snowblind, that the multi-GPU rendering mode brought about a negative performance gain, and not only with CrossFire but also with SLI. It means that the problem must be in the game rather than in these two technologies. In the majority of applications we have observed a performance growth ranging from 10-20% in F.E.A.R. (probably due to some problems with SuperTiling) to 80-90% in other games. In three more games the speed proved to be limited by the CPU performance despite our using full-screen antialiasing.

We were also pleased with excellent stability of the CrossFire platform which never hung up and never produced any image artifacts during our tests. This is another sign of maturity, we guess. ATI CrossFire does work now and it works quite well.