Thought I'd document this here, both for feedback and so others can learn from my eventual success or failure.
 
My family's about to get a bit bigger, and the home office is becoming the baby's room. My PC is moving to the bedroom. To save space (and hopefully look cool as hell), I'm going to mount my rig on the wall. There are lots of commercial wall-mounting kits for PCs. They are almost all too small for the DG77, even the purportedly 'universal' mounts.
The best I could find was the 4"-8" version of this mount . It measures approximately 8" wide by 8" long by 7" tall. It's rated for 40lbs, which is about how much my PC weighs, so I'm going to swap at least the top two, if not all, of the included drywall anchors with molly-bolts. Why are there no studs in my walls? Who knows, but I've made a lot of holes, and haven't found any regardless of what the stud-finder said.
 
I'm going to position the mount under the center of mass of the PC (slightly towards the back due the the weight of the PSU and 1080Ti FTW3).  To reduce weight and thickness, I am going to remove the left (main access) glass panel, since there should be little risk of anything getting at that side of the case through the drywall. Sadly, due to the layout of the room, all my pretty LEDs have to end up facing the wall. If the gap is really big, I'll point all my case fans inwards and call it a feature.
I am also going to experiment with mounting without the right side glass panel, with the bracket instead braced against the steel chassis rather than bracing against the glass, and then attaching the glass panel. If it goes well, this will also let me hide the side of the mounting bracket inside the glass. 
I will probably put small hooks in the wall near the top of the case, not to support any weight but to hold it against the wall in case the bracket starts to sag. My greatest worry is that the height of the case will turn any sag in to enough force to peel the mount out of the wall.
 
I'm open to feedback, and will report back after the mounting bracket arrives next week!

Thanks for moving my post.

The drywall appears to be supported by thin metal framing, based on past experience trying to drill in to 'studs'. My detector says there's one that I can probably line half the mounting bracket with. It won't support a screw against shear the way wood would, but I think I'll at least help resist tension better than drywall.

You're absolutely right to bring up the risk of it falling on someone. Luckily, I should be able to position it to land on my monitor and glass desk instead...

Definitely make sure you are grabbing on to studs, would be tragic and dangerous if that falls on you guys. Maybe an open post rack would work if you cant find studs, or they make some anchoring screws for drywall I believe too

Alright, here we go. A bit of a delay because, well, baby, but everything came together. Rather than bury the lede, here's how it looks:

Equal parts awesome and terrifying, right? Especially if you've ever picked up a DG77 and noticed that the case alone weighs 10 kg.
 
The whole setup is held to to the wall by four of these toggle-bolts from the local hardware store.

I originally was planning to use molly-bolts, but one I started drilling, I discovered that this wall is made with thicker drywall than the rest of my house, and the bolts wouldn't fit right. Ultimately, toggle-bolts seem to be considered more heavy-duty, so I'm happy for the switch.

To get them in, I had to drill 1/2 inch holes then file them out to square slots. That's very easy to do in drywall, and a real pain to do even in the fairly thin steel framing 'stud' behind two of the holes. Christmas provided, and my family were around to help out. Shoutouts to my father and brother for humouring me and supporting this wild project. They are the ones who accomplished this.
 
Here's what I have holding it up. It's the larger size of the Universal Equipment Wall Mount ordered from RackSolutions.com. There's a second nearly identical steel bracket that attaches to this one via those screws at the bottom to clamp the tower in from both sides.

That's the absolute largest PC mounting clamp I could find - turns out those are mostly made for SFF office-computer type cases rather than even mid-tower enthusiast equipment. All the same, I had to take off the wall-side glass panel to make things fit. I considered taking off the outward facing panel too, but it ultimately seemed like a better surface to clamp than the whatever I could jury-rig against the metal underneath. The only slight modification I made to the bracket was to move the rubber pads from the end of the wall-side bracket to the corner of the outside bracket, so that my case is being supported from its edges rather than from two points in the center of its lower surface.
 
Per my brother the engineer's suggestion, I may pick up a pipe/strut/brace to run from the floor to the bottom of the mount in behind my desk, which would do double or triple duty as a support, a cable conduit, and perhaps even a monitor mount. Structurally, my goal isn't so much to provide additional vertical support as to combat sag in the bracket that lets it lean away from the wall, so I may just opt to do this with another long corner brace mounted to back wall instead.
 

Cool , thanks for the updated pics..
 
You don't have to worry about the cat or a baby getting to it  way up there...

A very interesting mod. Looks great. 

Wow, never thought of wall mounting my radiator. Might use mine to keep my toes warm!

you must not live in an earthquake prone area, i could never do this

Oh, I owe y'all a (final?!?) update.
My spouse helped me paint the strut black, and I picked up an RGB extension because the connectors for the LEDs on the 3080 rad are shorter than the tubing. 
I swear the cables are also beautifully managed, but the desk obscures half of them anyway.
I'd say it all came together perfectly.

I looked at the Thermaltake Core P5 a while back and thought it would be cool to wall mount a PC like this.  
 
Had you not fitted the extra strut and painted it, I would have recommended a D-Line Cable Raceway.  They make a beige one which would blend into your wall pretty well without painting (although it is paintable).
 
Also, given that you don't have the constraints of the case for your radiator, you could fit two more fans on the other side and have a push pull setup for even more cooling!
 

Looks awesome. Very unique.

Good idea, never thought it myself. You can save a lot of space like that.

 
Interesting. Or ..you could have just put a shelf up there and sat the case on it. ¯\_(ツ)_/¯