For ATI Radeon X2 cards we simply start by inserting the two cards into the upper x16 PCIe slots. Now it's a question of connecting the power supply connectors. Again two sets of 6-pin and 8-pin connectors are required for the 4870 X2 cards.

Once you've connected the power cables, you need to apply the Crossfire bridge (barely visible in the photo) that you should have received with your mainboard. Typically there are actually two fingers on each card, it doesn't matter which one you use. Rules of connection:

• 2-way Crossfire > Connect both Crossfire bridges.
• 3-way CrossfireX > Connect the 2 bridges crossed.
• 4-way CrossfireX > Internally two GPUs are already bridged. You can only have one bridge in-between the cards connected.

Thus: the Radeon HD 4870 X2 therefore has one CrossfireX connector, connect it and we can now boot into Windows.

Also here applies the rule; please make sure you have removed all older Catalyst drivers by properly uninstalling them.

Once you have your system ready you can have CrossFireX powered up, and you are ready to roll within a minute, as it really is that easy to do. Once we boot into Windows Vista we wait for the Vista driver wizard to finish. Now you need to install the latest ATI Catalyst drivers. Just follow the driver wizard -- it's a fairly uncomplicated installation. It might take a while before everything is installed properly though. I've seen the installation procedure take up-to 15 minutes.

After the installation finishes, give the PC a reboot and you are good to go. If needed run the installation process twice.

Once you have four active GPUs installed, the Catalyst Control Center will recognize the CrossfireX setup. It'll report back to you that is has enabled CrossfireX. Should this not be the case, just go into the Catalyst Control Center panel, advanced mode, and have a peek at the CrossfireX tab where you can enable/disable the setup manually as well. If you can't enable it, something went wrong with the driver installation.

Once the process has finished successfully, we are good to go for quad-core gaming. Mind you that due to the nature of Catalyst drivers, you'll likely be reinstalling a new driver each month. Catalyst drivers do not have user based profiles in which you can enable CrossfireX support manually with a new game.

Overall this is the biggest hinder for both NVIDIA and ATI multi-GPU gaming ... the platform is as good as it's latest driver. And at times that can suck big-time as some games are not supported when released, regardless of profiles.

Photo of the 4870 X2 CrossfireX setup.

Two Radeon HD 4870 X2 cards setup in CrossfireX mode. Same rule here .. connect ALL power connectors, 4 cables yes Sir.