I haven't spec'd out intel boards in the past 12 months, so I'll go with some basic rules I apply to speccing out.
Get the latest generation mobo, but not necessarily top of the line board because I like Adaptec RAID cards. Get USB3 though, even though none of the forensic hardware guys support it. Tableau et al need to pick up their game. SATA 6GB for your SSD connection. Your choice on whether you can justify Dual Xeons, but chip wise I'd likely aim bottom of the 6 core chips. I look at the benchmarking sites and find a sweet spot of speed to cost.
OS/Apps Raptor
If you were running FTK3 DB on SSD. It's very noticable how much performance picks up going from 10kRPM drives to SSD for DB.
If you're not running FTK, any temp/swap files on SSD
I have an Adaptec 5805, and have 2 RAID5 4 drive sets connected, one for the images and one for the case files. Haven't had a real need to update to a SATA 6GB card yet. The image raid is much larger than the case files one. Running 7200RPM drives in the RAID, Caviar Blacks. They run a little hot, but Tom's rated them really fast for desktop drives when I was researching over a year back. Had 1 fail, but that's not a statistical sample. Hard more than 1 Seagate fail over the years.