Prices and availability have changed greatly since this build - I paid ~USD $1,200, with the potential to bring it down to ~USD $1,000 if I had bothered to send in all the rebates at the time.
First ever gaming build to retire my 2009 17" MacBook Pro from "gaming" duties, insomuch as the GeForce 9600m GT 512MB chip in it was barely able to run anything made within the past five years when running Windows 7 in Boot Camp. Initially I considered doing a slim build using the gorgeous Raven RVZ02, but I decided the thermal limitations and tight working space might be too ambitious for my first full build ever. I also like the idea of having room to expand to a fully internally mounted liquid cooling setup in the future. Will that ever actually happen? Who knows!
The Define Nano S practically handles all of the cable management for you. It really is a dream to work in, but then it is rather large for a Mini-ITX case. Fit and finish is phenomenal for the price. You will never be lacking for space, and the width comfortably takes the Noctua CPU cooler that is easily the size of the entire motherboard cubed. You can't even see the motherboard behind it except for the PCI-E slot. There's plenty of space to tuck things behind the tray, which also serves as the mounting point for 2-3 SSDs and a 3.5" HDD storage drive if you so desired. There's a kick-out to the tray in front of the motherboard to tuck away excess cable length from the PSU and to accommodate the thickness of a 3.5" drive, but the cable pass-through doesn't line up perfectly with the side-mount SATA ports on the motherboard, so the kick-out effectively blocks off ports 0 and 2. The case does keep things relatively quiet, which was one of its design parameters in the first place, but you can still hear the case fans and cooler; they're not silent at idle like the cooling fans in my old MacBook Pro. But then, under load, it's not nearly as loud as the cacophony of the MacBook's fans spinning up to 6000rpm just to keep the chips under 75°C. Oh, and one last thing I don't like aesthetically is blue power/actvity LEDs, I would prefer white or amber, but that's just a matter of taste. Turns out the LED's are held in with hot glue, so if I ever felt really ambitious I could change them out. Would I use this case again? I would consider it, but its conservative, functional style would be up against the similarly priced and more interesting looking (but still not too flashy) Phanteks Enthoo Evolv ITX series.
Because the CPU cooler is so massive, the board absolutely needs to be installed in the case first with all the cable hookups already in place. But that's okay because most of the motherboard is accessible from behind the motherboard tray, and is covered by an easily removable bracket for mounting twin SSDs. It completely covers the front panel USB 3.0 header and the plug only just had enough clearance under the heatsink to fit, though it is bent at an uncomfortable angle and is contacting the bottom fin. The Noctua heatsink also comes with a generous tube of good quality thermal grease that actually performs better than Arctic Silver 5, so that's a plus, and it comes with a surprisingly high quality metal cloisonne case badge. Which is a shame, because I hate putting manufacturer badges on cases. So I stuck it on the side of the square fan to be seen through the window. Then today I came home to find it had fallen off for whatever reason, which is a little bit surprising given the 3M adhesive tape on the back.
The overclocking utility included with the Gigabyte motherboard brought the max clock of the CPU up to 4.3 GHz on all four cores simultaneous, an 8% improvement over the stock turbo boost frequency of 4.1 GHz. But then, stock turbo mode is only on one core, while it goes down to 3.6 GHz when running on all four, which means the four-core overclock is effectively 19%. It's nothing crazy, but it is a respectable number and I didn't build this rig for high-end overclocking anyway. Haven't gotten to attempting faster settings on the RAM yet. I've always been of the mind that gains in gaming from buying more expensive, faster RAM were minimal and not quite worth the added cost over a good quality, more modestly clocked set. However, many features included in the mobo app suite (including many non-overclocking-related features) lack any explanation as to their function or use. Edit: Used Intel's Extreme Tuning Utility and brought the clock speed up to 4.5GHz. The NH-D14 keeps it at a relatively cool 54°C. Hooray for modern low-TDP CPUs. Realized I hadn't set the RAM to use the recommended XMP profile, so it had been running at the default DDR4 speed the whole time. But after that, I couldn't adjust timing settings any faster without crashing because I'm completely out of my depth overclocking RAM.
And yes, a 450W PSU is plenty for this build. Even cautiously high estimates still put the power draw at only 60% of its capacity.
Full disclosure, the GPU is not in the system at this time; it is due to be added come the holiday season. But even the on-board graphics of the i5-6600K blow the discrete GeForce 9600m GT mobile chip out of the water, so for the games I've been running in absence of modern computing power, it's more than sufficient. Edit: Installed. Overclocked beyond the factory overclock using the Valley benchmark to test for stability, but had to dial it back further due to crashing in a few games. Worth noting is the rear fan of this AIB design is completely smothered by the PSU. A blower-style cooler might perform better in this situation. Also, when the GPU fans ramp up to a certain range, there's a bearing rattle, but it goes away when the fans go up higher…and it's not just because they start to sound like a jet engine. Thankfully, under typical gaming load they don't usually spin up that fast. The Define Nano S has really good airflow for a Mini-ITX case.
A couple of rookie mistakes from this being my first ever ground-up build: First, I bought the OEM disk for Windows 10 Home, but as you can see, there isn't an optical drive to be found. I had to run out to the store to get a cheap external DVD burner to load windows and the other install disks that came with the motherboard, though I'm sure I could have just downloaded the Gigabyte software off of the website instead. So the money I saved by going with the OEM disk instead of the consumer USB drive instead went to the optical drive, which I guess could still be handy to have. Second, I realized far too late in the build (read: after it was completely assembled the first time without the GPU) the way I routed the front panel USB 3.0 cable was going to interfere with installing the GPU when I finally got it. This meant taking the CPU cooler off to unplug and re-route the cable when the time came. Third, and least important, I should have plugged in the splitter pigtail for the CPU cooler fans before mounting the cooler just like all the other cables. I hadn't considered it could be installed before the cooler to make plugging in the fan leads much easier; so instead I struggled to get it onto the mostly obstructed fan header with minimal clearance above the motherboard to reach in, but I eventually got it.
Oh, and I hadn't noticed the board had an M.2 NVMe slot on the back to mount an on-board SSD, so that was a missed opportunity. I probably would have gone that route for a system drive if I were to do it over again, it would reduce some of the wiring clutter hidden behind the motherboard tray.
You won't find any flashy lights or anything like that in this build for the time being. Function took priority over form. And with a cooler this big and a motherboard this small, a window is almost a waste because you see the cooler and that's about it. I bet it's a whole lot more impressive with a full water cooling setup. What you will find instead is a banana, for scale. It really is hard to convey just how big the cooler is and just how tiny the Mini ITX form-factor is in photos without something to compare to.
Edit: play-by-play on Imgur Edit 2: GPU is installed and relevant performance data updated. Viggen badge added now that it has performance worthy of the badge's origin.
Also, I don't know if it's the audio chipset on the motherboard, the chipset software, or something with the case hardware itself, but the sound from the front panel headphone jack is absolutely awful. You're better off running an extension off the audio out on the back of the motherboard, or plugging into a monitor if it has built-in speakers and a headphone out like mine does.
Update Dec. 2017: added 2TB WD Gold storage drive, not shown in pictures. It's mounted on the bracket behind the motherboard tray, towards the front, next to where all the cables are stuffed. Despite what might seem like a lack of adequate ventilation, I've yet to see drive temps exceed 40°C.
Update May 2018: I now have a single NF-A12x25 PWM on the NH-D14, ordered on launch day. A12 has changes to the fan frame that interfere with the mounting clips for the D14, I had to trim the clips so they just barely fit the new fan. The stock voltage-controlled fans that came with the NH-D14 replaced the Fractal Design case fans using rubber anti-vibration mounting pegs that came with the A12. The NF-P12 that came with the cooler is now acting as case exhaust mere millimeters away from the back of the CPU heatsink, basically keeping two fans on the heatsink even with only one mounted to it. It still works great, and even quieter. I have the fan curves set up to shut off case fans at idle, and keep both fans at lowest possible speed under low load. Idle temps are a bit higher at 30°C on the CPU, but it's dead silent with only the CPU fan running. Adding the HDD in 2017 added a lot of noise to the system when I wasn't expecting it. Turns out you can configure a drive to optimize for Quick Removal and it prevents it from spinning up randomly for write caching. Bonus, it's less prone to data loss or corruption in the event of power failure. Now it's dead silent except when loading games, which is fine. Since it's not the primary drive, the performance hit of disabling write-caching isn't really noticeable.
Update February 2019: The CX450M semi-modular PSU had an oopsie and took out the SK Hynix 512MB SSD. Lost some stuff I'm going to miss. I replaced it with a Seasonic Focus+ Gold 550W full-modular PSU and an Intel 660p 1TB NVMe as a replacement boot drive, but the motherboard had to come out for it. New PSU is a bit quieter and often runs in completely silent mode, but there's still some annoying fan motor noise (PWM noise perhaps?) when the fan is running at lower speeds. Took the opportunity to improve the cable routing and management, looks even cleaner now from the back side.