For a PC without a powerfull GPU I believe the best solution is a case with heatsinks, feks HDPlex, Streacom and HFX. The heatsinks work best outside the case where the air is cooler. We have build a HDPlex H3: http://www.hd-plex.com/H3.SODD.html
with a i7 3770, 160W PicoPSU w/192W adapter, Corsair 8GB 1600MHz LP RAM, Samsung 830 256GB SSD, Sony Optiarc BD-5850H, Asus P8Z77-i deluxe motherboard and Windows8. The PC is very fast and plays blueray without a problem (but you can't use the full PCIE slot with this case. 6 heatpipes is overkill so if you cut one pipe out, or the two lowest pipes, you probably can get space for a PCIE X1 or X4 flexible riser cable. If you need full PCIE slots there are lots of alternative heatsink cases).
For a CPU with only 45W tdp the case is eaven more safe. The case only uses the heatsinks on one side to cool the CPU. With a motherboard that have room for heatpipes to both sides, the case could be modded with three heatpipes to each heatsink (HFX sell heatpipes and each pipe can take 33W). The H3 is recommended for max 65W tdp, with two sides active this means 2x65W=130W tdp (within recomended cooling capacity). With both sides active the case probably could cool of i7 3770K on full load, and maybe some overclocking aswell. To run only the CPU I think the PicoPSU should give enough power. Or you could place an ATX powersupply, like the one you suggest, on the outside. I have done this with a Streacom FC5 with a discrete graphic card http://www.silentpcreview.com/forums/viewtopic.php?f=23&t=65196&start=30
If you need 16GB RAM you may go for a micro-ATX motherboard and a bigger case (I don't know if there are any 2x8GB RAM in low profile).
With the fast development of integrated graphics I think small cases with heatsinks will be more and more popular. In spring Intel say the Haswell CPU will have twice as good graphics as the AMD has today and play most games in HD. A midrange gaming pc in the HDPlex H3! It will be interesting to see... (edit: I may have been a bit optimistic about Haswell and that it will be double of the HD4000, I am not shure. Maybe it is AMD Kaveri APU that will be the next big step, they say this is based on the HD7700 series.)
By the way, HDPlex has in our experience very good customer service. (we where lucky to get hold of a H3 with silver front though, they are often sold out)