"Green" is almost certainly not the manufacturer of your motherboard, but a label that indicates that it does some sort of power saving or other. So unfortunately you're not telling us anything other than that there's an Am486DX2 at some or other speed in there...
Back in the days of the 486, you generally had a shitload of jumpers to configure on a board for any given CPU. If you haven't got a positive ID on the board, you can't have checked whether the jumpers are set correctly for your situation. Not having any other information, I'd guess that that's the most likely cause. But that's just the biggest needle in a huge haystack. How about getting A LOT more specific?
- which Am486DX2?
- if you can't ID the board yourself, give us more to go on. A sharp, hi-res picture might do the trick
- which PSU? Is it known to work with other systems?
- which adapter?
- which Trident video card (or at least: which Trident chip on it) and where is it plugged in? Is this known-good too?
- what sort of monitor are you using? Have you seen DOS-era stuff work on it before?
- is there any RAM in the board? If so, what type, how much and in which slots?
- what else is connected to the motherboard? (be specific here as well)
If I had an unknown board, my first steps would be:
- ID the board if at all possible
- check jumper settings for my CPU
- hook up the bare minimum of known-good parts, so RAM (4x 30p SIMM or 1x 72p SIMM in the case of 486), CPU, VGA and keyboard.
- try and boot
- use my Port 80 debug card in case of doubt. These things are overrated for pinpointing the exact cause of a problem, but are great in telling you whether the board is doing absolutely nothing (something very fundamental is wrong), starting to boot but hanging somewhere (usually a timing/setting issue) or actually booting perfectly, just not showing anything on screen (VGA card and/or monitor involved).