The ASRock 775XFire-eSATA2 is ASRock's first motherboard which is able to run Crossfire. Intel's i945 chipset has enough PCI lanes to do that. 16 lanes are used for the primary PCI-E interface and 4 are used to implement a second PCI-E port called "AGI". Effectively this means Crossfire runs at x16/x4. While the x4 might worry some people I do not see much of a problem there as long as you use cards that have a loopback cable. So X1300 and X1600 are out. The rest should work fine without performance loss. When a game starts it uploads all geometry and texture data to the video card which renders from there - the PCI-E bus is barely used.