I thought I'd let anyone else know of the troubles I ran into with my F18A installation.
First and foremost; this is an absolutely awesome piece of hardware, but then I knew that when I bought it. If you don't have one, you should!
Anyhow, I started the project, oh about 3-4 years ago, and unfortunately, it never seemed to work right from day one, for me. It was very intermittent. Sometimes it would work, sometimes it wouldn't. And when I say it wouldn't, I mean the console wouldn't turn on, zero video, zero sound, zero anything but a power light on the TI power supply.
I'd wiggle the cable, turn it off, turn it on, sometimes it would come back, other times it wouldn't. I tried different monitors, different video cables, I even changed out the VGA ribbon cable (internal one), to no avail.
I tested it with the bare motherboard on the desk, and it would work. Soon as I put it in the TI case, it would flake out again. I did use the original RF shield, and really wanted that in there. I checked for shorts to see if it was hitting the F18A, but there was plenty of clearance. I tried just about everything, and figured it was a faulty TI socket, gave up, and let it sit for a couple years (sad I know).
However, since I had the burning desire to get that thing working, I sat down yesterday and fiddled with it until I finally found the problem!
The stupid VGA ribbon connector was shorting out on the RF shield! Both of my VGA ribbon connectors (two completely different brands) both exhibited the same problem. Let me repeat that, the ribbon cable, not the F18A was shorting out. Certainly wasn't my first thought, or tenth...
Hopefully, this will help someone else cut down a couple years of wasted non-enjoyment, out of the awesome F18A.
Here was my final solution, and it hasn't flaked out since! (double yay)