Here's the full environmental specs on the unit:
Looks like they specify a maximum of ~42 watts usage by the system.
Do you mean, what's the maximum temp of the CPU, or the max temp of the room in which it is being operated?
Depending on the CPU, max temps will vary a bit, but I'd say anything over 75C is probably a bit toasty for a Core Duo or Core2Duo CPU--although most actually are spec'd to operate a bit higher than that.
The warmer the room, the more work the fans will need to do in order to keep the CPU/GPU in "safe" ranges...
Are you seeing temps reported by a utility that you feel are a bit too high?