Peter
The earlier person is not correct.
The Board supports 2.8 Ghz at either 533 or 400 Mhz after upgrade to newest bois version.
Because the power supply in integral to the chassis and the pinning is non std it is possible to put another nonstd(re non Compaq/HP )powersupply in their but a lot of work will be required to repin the atx connector.(A lot easier to use std power supply)