[giant25]

Well, made more progress. Turns out I had a lot going against me. Sure enough, the latest firmware on the Samsung 4k TV released this week resolves some HDMI signaling issues. I was still having some issues besides this and realized that I connect the Chromebox via HDMI cables going through the wall. These cables turned out to be older "Standard" HDMI cables, and Samsung noted to use High Speed HDMI Cables only. After bypassing this cable (which I had tried before with older firmware and no success) and using a newer High Speed Cable I have (HDMI 2.0 compatible, although I'm sure 1.4 would work, too), the Chromebox BOOTS NORMALLY, as does ChromeOS. This is all only true if that "UHD Color" setting in the Samsung TV is ON. I decided to set my resolution at 1080p since the 4k res looked a bit choppy, especially when playing back some of my mpeg2 TV recordings. So yeah, combo of firmware update, cabling change, and UHD Color setting got me there. Now I just need to run some new HDMI cables through my wall!! Thanks for sticking with me Matt, hopefully this helps other folks that will start coming along with 4k TVs.

not sure why the UHD color setting would have any effect, sounds like it does more than just that. The ChromeBox is limited to 30Hz output via HDMI at 4K, due to having a HDMI 1.4 port, and this would be especially apparent with 60fps material like broadcast TV. If you want 60Hz output, you'll need to use a DisplayPort 1.2 to HDMI 2.0 adapter, such as this. I haven't yet tested it myself, but do have one ordered, and plan on testing on a friend's 4K set.

I would like to go 4k @ 60 Hz, and I've read about that adapter (not in stock anywhere!). Definitely post if that works and I'll do the same.