Form Factor Discussion
When we talk about form factor we're concerning ourselves with matters of PCB and cooler size, power draw, heat output and noise. All of those things are interconnected on various levels making talking about them as a whole a useful exercise. If we're correct and all Radeon X8-series master cards all share the same dual-slot cooler then Crossfire stumbles and nearly falls flat on its face just because of it.Here's what we said about the Crossfire cooler as applied to the Radeon X850 XT Platinum Edition reference board.
Should your X850 XT Platinum Edition sport this reference cooler and should it have cause to spin its fan up to 100% while gaming or otherwise being worked hard, be prepared for an annoying, high-pitched, loud noise as the blower does its thing. That would give me cause to complain, but since it never happened during testing, it comes across as a well designed thermal solution for the board.To test the coolers properly, we prepared a fully built and integrated Crossfire system based on X850 Crossfire (X850 XT clocks for master and slave and both using the same cooler) and a Coolermaster Wavemaster chassis. The popular and stylish chassis has been used in SI integrations of high performance systems in the past and its well placed intake and exhaust fans give it decent if not class-leading interior thermals.
Playing Half-Life 2 in AFR mode at 1600x1200 with high levels of IQ (although not Super AA) for an extended period (all in the name of serious evaluation you understand!) caused the coolers to both spin up to the full-speed that caused us to write what we did at the X850 XT Platinum Edition launch. One cooler of that sort is bad enough at full speed. Two in the same system is truly horrible in this reviewer's opinion. I'd even go so far as to call it easily the most obnoxious graphics setup my poor ears have had to suffer.
The fans on both cards appear to spin in lock step with each other, too. If one gets hot and spins up, the other does too at the same time. Not good. Not good at all. NVIDIA GeForce 6800 Ultra in SLI would likely be even worse in terms of chassis thermals with their reference cooler unable to get hot air out of the chassis in any fashion, leaving you to rely entirely on the chassis's own thermal performance to get rid of the heat for you. However that fact doesn't make the ATI reference cooler for X850 Crossfire any quieter and it's the noise that HEXUS object to most, chassis thermals a more easily solved problem than changing the coolers on your expensive graphics hardware.
In terms of power, HEXUS was able to power the fully assembled test system, complete with Athlon 64 FX-57 system, 2GiB of DDR400 system memory and single 10,000rpm Raptor hard disk from a Tagan TG420-U02 420W power supply without any problems or stability issues.
In size and cooler terms, the dual-slot cooler will do you the same lack of favours that dual GeForce 6800 Ultras do on the SLI side of the fence, the biggest issue being that slots under the coolers become unusable.
Summary
Hot and very obnoxious with both tested boards at full speed, the X850 Crossfire cooler does a full Crossfire system no favours, especially if you have that same assembly on your slave board too.Be aware that manufacturers don't provided validated noise data for their coolers and HEXUS is unable to verify the absolute noise levels obtained, leaving the commentary on the noise a subjective one. However we fully stand by the subjective statements believing them to be valid even without empirical test data to verify the statements being made.
