If my customer wants 2U chassis (short depth), I select 825MTQ-R700UB
http://www.supermicro.com/products/chassis/2U/825/SC825MTQ-R700U.cfm
Which models of motherboard can optimize if he needs i7 core CPU?
If impossible, what are other motherboards we can consider?
X8ST3-F/X8STE will be the best choices. These two are optimized for 825TQ.
http://www.supermicro.com/products/motherboard/Xeon3000/X58/X8ST3-F.cfm
X8SAX could fit in the chassis, but you cannot use 2 PCI-Ex16 slots for Nvidia SLI technology.
X8STi(3) series could also fit in, but the heatsink might have interference with chassis, not recommended.