Had a colleague approach me for building a machine for AutoCAD and Revit for under 900 bucks (CAD). After a little back and forth, I think we came up with something pretty decent. Keep in mind, this is not a gaming machine and never will be. Also, the 500w power supply ended up being cheaper than any smaller PSUs that weren't complete crap.
http://ca.pcpartpicker.com/b/GSb
CPU - Intel Core i5 3570 (Stock cooler)
Motherboard - Gigabyte GA-H77-Wifi Mini ITX
Memory - Patriot Viper 3 8gb @ 1866mhz
SSD - AData XPG SX900 128gb
HDD - Seagate Barracuda 7200 rpm 1tb
Video Card - Asus HD 7770 Ghz Edition 1gb
PSU - EVGA 500B
Case - Bitfenix Prodigy - Black
Optical Drive - Whatever he found that was cheapest
Cool, wasn't criticizing....really is a cool looking machine for the job!
I use AutoCad Inventor and just saw you say AutoCad Revit so my brain went AutoCad + rendering in 3D = if I spin my SpaceNavigator 3D Mouse as fast as I can my GPU gets hot enough to make toasted sandwiches while I wait for it to finnish! (I guess its not the best way to use CAD or make toasted snacks though!)
I see your point. Inventor and Revit can become quite GPU heavy once you load your model with ridiculous amounts of information. Sadly, he will only be doing simple houses and single-storey commercial buildings with not a lot of intricate details, so only lukewarm sandwiches for him.