I actually just set one up (though in a temporary case while I wait for a few potential options I like better).
I went high-end on mine, so it's a little different than what both of you mention, but the goal is going to be that it'll replace my main gaming and media PC as soon as I'm sure everything is working properly.PCPartPicker part listCPU: Intel Core i7-4770S 3.1GHz Quad-Core ProcessorCPU Cooler: Noctua NH-L9i 57.5 CFM CPU CoolerThermal Compound: Arctic Cooling MX4 4g Thermal PasteMotherboard: ASRock Z87E-ITX Mini ITX LGA1150 MotherboardMemory: Crucial Ballistix Sport 16GB (2 x 8GB) DDR3-1600 MemoryStorage: Plextor M5M 256GB mSATA Solid State DiskVideo Card: EVGA GeForce GTX 780 3GB Video CardCase: Cooler Master Elite 120 Advanced (Black) Mini ITX Tower CasePower Supply: Silverstone Strider Gold 450W 80 PLUS Gold Certified SFX12V Power SupplyOperating System: Microsoft Windows 8 Professional (64-bit)Other:
Panasonic UJ-265A Blu-Ray WriterOther:
Slimline SATA AdapterOther:
Western Digital WD10JPVX 1TB SATA3 2.5" HDDOther:
Inteset Internal USB IR receiver
I had a bit of a scare with the motherboard socket pins, which got bent during the CPU install even though I did things properly. After I confirmed Newegg wouldn't accept a RMA on it, I bent the pins back into place myself and (shockingly) everything is working fine. I wanted a motherboard with built-in Bluetooth and Wifi, even though this PC will almost always have a wired LAN connection, because of potential Wifi Direct features and because I didn't want a dongle anymore for Bluetooth like I've used in the past.
Even though this temporary case supports a full-sized ATX PSU, I went with the smaller SFX one for flexibility in permanent cases; the same goes for the slimline Blu-Ray drive. (My current preferred case, for what it's worth, is one that a guy on Hardforum is machining. If he makes more of those, it's likely I'll go with that.) The Elite 120 is a cube case, but I'd prefer something not nearly as tall, that instead uses a PCIe riser for the GPU.
Anyway, the 450W is more than enough for this system, which is using ~330W (according to my Kill-A-Watt) while running Furmark and Prime95 together. It idles at about 30W.
I really wanted the GTX780 for a few reasons, even though it's probably slightly overkill. One is for gaming in stereoscopic 3d, which I still do occasionally and so I wanted extra power there. But also, I really like the Titan-style cooler for a smaller case, since it doesn't just recirculate air inside the case, but blows it out the back.