This is a great chance to pick up one of the last and best owner controlled x86 boards for much less than the usual price ($350) and MSRP ($315).
Compatable with Qubes 4.0!
Supports IOMMU for graphics! (so you can play video games in a VM)
CPU's cost around $10-50 and 16GB DDR3 ECC RAM is $30
Recommended Accessories:
ASMB4-iKVM (BMC Module, required for the upcoming libre OpenBMC port for KGPE-D16/KCMA-D8 the asus boards)
TPM (Coreboot supports an owner controlled core root of trust which is more secure than otherwise)
Note:
128GB RAM Max
You will have to get a graphics card if you want decent video, the onboard chip only supports 1280x768 and is quite slow - AMD is reccomended for better virtualization (see nvidia code 43 "bug" when you try to attach their cards to a VM) and linux drivers that are almost open source and don't suck unlike nvidia
43xx CPU's require microcode updates for secure operation
Reccomended CPU's:
4284 (Works securely without microcode updates)
4365EE (40W, for a low power build)
4386 (equivalent to AMD FX 8310)