I also ran Apple Hardware Test (boot from the Mac Pro system software DVD while holding down the “D” key). With 10GB of memory, it takes a long time, even for the short test, so long that I thought it had crashed or hung. But after somewhere between 7 and 15 minutes (guesstimate), it passed just fine. The fact that the mouse cursor responded 20 seconds or so after moving the mouse led me to believe that the test had crashed or hung. I never was successful in canceling the test, reinforcing my concern that it had crashed or hung. Fortunately, it is just really, really sloooooow. Apple should clarify this point for those of us with gobs of memory.
The wonderful thing about the Mac Pro is that even under full load for most of an hour, it remains barely audible, at least under my desk. The Intel Xeon “Woodcrest” processors must indeed generate less heat than the PowerPC G5 processors.