Horizontal Steambox Brainstorming

[Rhino]

So here's what I'd like to do: Build a steam box that will sit horizontally on the shelves of the entertainment center below my TV. The shelves are a bit over 8" in height, which means I'm looking for something like an HTPC box, but for gaming. Our TV is just 1080p, so I don't need 4K support, and I don't really need DVD/Blu-ray support either, since we already have a Blu-ray player (almost never used since we use streaming).

Initial thoughts: Some kind of GTX-970, perhaps the Strix unless I go for water-cooled. Definitely nvidia for SteamOS.
Core I5-4460 should be fine for a gaming rig.
8 gb is probably enough for a gaming rig, although I could go 16gb -- doesn't really matter.
Prefer micro-atx to mini-itx (more power supplies, etc.), but could go with either.

Needs to be reasonably quiet, certainly near silent at rest.

Edit: Not planning to overclock anything, since I expect heat to be a problem in a horizontal case.

[CA_Steve]

Welcome to SPCR.

Airflow and heat dissipation can be problematic with horizontal gaming builds in tight places.

How much space is there for the width and depth of the case?
Is it truly a shelf (open in front and back) and not an enclosure?

[Rhino]

It's truly a shelf, open at the back. Horizontal width doesn't have a hard limit; it could easily be 18" width without issues. The shelves are glass, and are slightly curved (bowed), but are approximately 16" deep. The stand is not directly against the wall; there's probably another 4 inches of space behind it.

[Rhino]

I should add that I might be able to build a relatiely thin tower and put it next to the TV, but that space would also be somewhat close (there is the entertainment center on one side and media shelves on the other), and I suspect I'd have issues with the steam controller connecting to its usb connector (the path might be obstructed). Obviously there are potential work-arounds (use a usb hub or something to put the usb connector below the TV), but it really would be cleaner if the case could go below the TV.

Budget is not infinite, but probably not the big limiter, either.

[CA_Steve]

The Silverstone Grandia GD09/10 for horizontal, or perhaps the Silverstone FTZ01 if you have enough space for vertical placement. You could go horizontal with the latter, but probably want to raise it up for better bottom airflow.

Hopefully, others will pipe up with more suggestions.

[Rhino]

I was thinking the Fractal Design Node 304 might work, since the ventilation is mostly fore/aft with a little on the sides, not top to bottom. It wouldn't have a lot of clearance, but it would fit. Thoughts?