ATI CrossFire - Hands on

Use your existing cards

You don't need to buy two new cards to use CrossFire - just one. If you buy a X850 CrossFire Edition card, it will work with any other X850. If you buy an X800 CrossFire Edition card, it will work with any other X800 - simple as that. This makes upgrading from one card pretty easy.

Does it work?
Yes. We plugged in our HIS X850 XT alongside the CrossFire Edition card and it worked flawlessly.

Not all good

Of course, the technology behind CrossFire isn't all good. The one, much talked about limitation of CrossFire is its inability to render at above 1600x1200 at 60Hz.

Why is there this limitation? Well, we know that CrossFire uses DVI to composite the signals of the two cards together in a dedicated Silicon Image chip on the Master card. The downside of this method is that there is only so much image detail the chip can process, and it appears to top out at 1600x1200 at 60Hz, or indeed, 1920x1200 at 52Hz.

Is this an issue? Well, in the interests of fairness, let's work it out.

This is a big deal!

Anyone buying two graphics cards wants to be able to run insane resolutions at top quality - otherwise, why else would you bother spending so much money? Large CRTs easily run 1600x1200, but running at 60Hz makes your eyes bleed - CrossFire should be able to easily manage 85Hz or even 100Hz for the kind of money a CrossFire solution costs. CRTs are still the best gaming displays out there - it's inexcusable that we can't run at a super resolution or at a decent refresh rate. Besides, a single X850 can do it - why can I play at a higher resolution with a single card than I can with two?

This isn't a big deal!

OK, this is being blown out of all proportion. There are two types of hardcore gamers that will be buying CrossFire - those with CRTs and those with LCDs. If you've got a CRT, forget about the high resolution - just stick it down at 1280x1024 at 85Hz (perfectly acceptable) and then whack up the CrossFire SuperAA to compensate for the lack of resolution - trust us, the image quality is fantastic. If you're running a LCD to game on, you're laughing - top notch 20" panels all do 1600x1200 at 60Hz, the same as CrossFire.

The Resolution (doh!)

The upshot is that the limitation will probably cheese people off a little. For games that support HDR on ATI cards, AA is often disabled, so putting on CrossFire AA isn't an answer to this problem (Splinter Cell: Chaos Theory is a title that comes to mind). Whilst it's possible to add AA on other titles, we generally prefer to add resolution to avoid everything looking so huge on a CRT. If you play on a LCD, you won't care.

We do not yet know if this is a limitation that will affect next-generation CrossFire cards based on the X1800 - if it is, the inability to do high-res, HDR gaming could well be a problem for ATI. If it isn't, there's no worries. As it is, you'll have to make your own call about whether or not you can live with it based on the monitor you use and your own preferences.

Bootnotes

There's nothing special about the CrossFire motherboard, apart from the fact it has two graphics slots. As such, we were keen to see if we could get CrossFire working on a SLI motherboard. After ripping the cards out, installing the drivers and much fiddling, we couldn't get the CrossFire option to appear in Catalyst Control Panel. The upshot - we don't think there's any reason, by way of technical specification, that it shouldn't work. However, ATI appear to have locked it out in the driver.

We noticed no degradation in image quality through the use of the DVI compositing system.

In terms of noise, CrossFire is loud as hell. A single X850 XT, with the dual slot cooler, is loud. Two of them together is ear-bleeding - but then, so is 6800 Ultra. We hope that the coolers on the X1800 cards are more like the noise level of the 7800 coolers, which are whisper quiet, and perfectly palletable in SLI.