I'm running a mini-ITX build under the telly at the office:
Intel i7-6700
8GB DDR4-2133
256 GB Intel 600 NVMe SSD
1TB WD Black 3.5in HDD
Gigabyte GA-H170-WIFI mini-ITX motherboard
Gigabyte GV-N1060IXOC-6GD short 6GB GTX1060 PCIe video card
Corsair Obsidian 250D case
Corsair 500W PSU.
Currently, I have an old DVD-RW drive in it as I'm ripping a number of our DVDs and putting them through Handbrake. Otherwise I couldn't care less what optical drive it has in it. I've got Elite

angerous running on it and it is noticeably smoother than the home computer (i3-3240, 8GB, Radeon HD7770, 1TB WD Black regular hard drive).
Only thing with it is that under heavy CPU load, the CPU fan winds up and is quite noisy. Also, I've only got a 500W power supply in it. I could have gone for less, as all the parts in it are relatively low power (i7 = 65W, GTX1060 6GB = 120W are the major power users) and the board only has a single PCIe slot. Perhaps I could have gone for the GTX1070 version of the card but it was almost twice the price with only a 40% performance improvement, and I'm not that much of a dedicated gamer.
I'll probably put together a Ryzen build at some point so I can evaluate the AMD stuff but they're still not here yet...