Doing normal work on my mac pro 2.8ghz stock and checked the temps with istat pro and the cpus are at 29c. Even feeling the back of the machine there is like lukewarm air coming out the back. Amazing. These machines are the sweet spot when you consider price, performance and power usage. My 8-core 3ghz last revision put out more heat and the cpus I think ran at 45c idle. Northbridge is at 37c. Now that is really good. Used to be around 70c I believe. Pretty amazed.