The space around the AMD AM2 CPU socket is tight, there may be problems installing larger heatsinks. The two MOSFET heatsinks are designed to work with exhaust airflow from the CPU heatsink fan. If you're going to go with something passive, like watercooling, make to install the the fan that's included with the M2-CROSSHAIR package on one of the MOSFET heatsinks here.

The rear I/O of the M2-CROSSHAIR is very busy which is why Asus includes a proprietary 8-channel High Definition Azalia audio controller. The slot which looks like a backwards PCI Express x1 slot will not work with other devices, but it's nice to have the ability to remove it, should you decide to install something better.

Asus has a very elaborate cooling system for the nVIDIA C51XE Northbridge and MCP55XE Southbridge. Heat from the Southbridge is moved to the Northbridge heatsink which is connected via two additional heatpipes that conduct the combined heat from the Northbridge/Southbridge to the two MOSFET heatsinks. The copper thin fin heatsinks are cooled by the air from the CPU heatsink fan.