CPU: Intel Haswell i7 4770T
http://ark.intel.com/products/75125/Intel-Core-i7-4770T-Processor-8M-Cache-up-to-3_70-GHz
This build is for server use, so an important CPU feature for me was VT-d, the K series don't support this so an overclocking chip was basically not viable. The S and T series chips are available in the UK retail market, which both have the visualization features I need, the S runs at 65W TDP and the 4765T is heavily compromised on stock and turbo clocks for the sake of 10W saving so this was the chip for me. I looked at the AMD 6/8 core chips but they were too power hungry / hot for a small case, and I also looked at the Xeons but discounted them (see motherboard). It's an annoyance that Iris graphics are only available on the soldered on chips, so HD 4600 graphics will have to do.
Motherboard: Asrock Z87 ITX
http://www.asrock.com/mb/Intel/Z87E-ITX/
I needed an ITX board for this build, this part actually took the most research. I'm installing RHEL 7.0 Beta here, so need components that are well supported in Linux, and again Visualization is key. This basically discounted anything with onboard Network that wasn't Intel. I also wanted an msata slot AND a mpcie slot, one for an SSD and one for a Wifi card. The best fit for this was the Asrock, it's the only consumer motherboard that has these things AND supports VT-d. The Asus Maximus was second choice here, everything else had Realtek / Killer NIC. The Asrock even supports Xeon chips, but not ECC RAM so it's pointless using a Xeon. All of the server or workstation boards I checked were missing one or both of msata and/or mini pcie.
Case: StreaCom F1CWS Evo
http://www.streacom.com/products/f1cws-evo-chassis/
It's tiny, about the size of a Mac Mini but taller. No clutter on the front. I last used an optical drive a couple of years ago, so a power button and LED is all I want.
PSU: Nano 150W PSU
http://www.streacom.com/products/nano150-psu/
No room for a big old PSU in this case, I'm okay with a brick tucked away somewhere out of sight.
RAM: Crucial Ballistix Sport DDR3 PC3-12800 16GB
I wanted more RAM here, but 16GB is it on MITX. These guys are very short so won't block the cooler and run at 1.35 with timings of 9-9-9-24
Cooler: Noctua NH-L9i CPU Cooler Low Profile - 92mm
http://www.overclockers.co.uk/showproduct.php?prodid=HS-024-NC&groupid=701&catid=2330&subcat=2346
Small, good brand, won't obscure anything
PCIE Slot: Intel Pro 2 port Low Profile NIC
I got this from ebay, it used to live in a Dell server. Adding this gives my tiny machine 3 * Intel Gigabit network ports.
Storage: TBD