So, I just googled your part number. It's not a JX30GC, it's a JX30G. Partial manual here: http://webpages.charter.net/dperr/micronics/900189.htm. Salient differences appear to be: GC version has dual IDE, this seems to have single; GC version also supports 3.3v CPUs (but not multiplier select; a 5x86/133 will run at 3x33, not the correct 4x33). So, DX2 is the limit unless you can find a DX4 Overdrive, Pentium OD or 5x86 with voltage regulator. Otherwise they're very, very similar boards.

Might have the same issues as the JX30GC, though. Mine wouldn't recognize a SATA DVD+RW connected with one of those adapters; I didn't try a hard drive that way.

Consider my hat smoked, but only partway!

EDIT: If you were to add one of these - http://www.ebay.com/itm/AMD-AM486-DX4-100-WIT … B0AAOSw9GhYl2xP, (not my sale) then socket a 5x86/133 with integrated voltage regulator onto that, I suppose you could get it working at full speed. Weird!

Yeah it doesn't like the VLB card but it ran fine on another one I bought. Though I did a silly and accidentally turned it on while messing with the BIOS jumper. I didn't know it would erase the BIOS so now it just turns on with this lovely sound http://k003.kiwi6.com/hotlink/481vpm17u4/Gate … 00errorbeep.mp3

I found a recovery disk for the BIOS ( JX30GPRD.EXE ) but it didn't solve the issue.

I had ordered a replacement board for it. Checked all the jumpers and everything. Turns on, but no video. Tried both VLBs, same result. If I turn on the machine without a video card, same thing (no beeps even!)

So I guess that board was toast.

Nuts!

It might be fixable if you have an external flasher. I have one, and could grab the BIOS image off my JX30GC, but I'm almost certain it's too different to work.

Incidentally, what was the chipset on the video card that did work?

Same one, just a 3985VL-15... Genoa 8500VL Rev A instead of a newer revision.

EDIT: I swapped out the lil' BIOS chip from both machines and at least I got one working motherboard!

Well, one working board is good news!

And I think I can add that as a data point. Those Genoa cards use various GD542X chips, and it's looking to me like the 5428 is the only one that works with these Micronics boards. So, if you need another video card, look for the Tseng ET4000/W32 or S3 83c805 chipsets, apparently. (Or the S3 Vision968, but that seems to be rare as hen's teeth).

Well, my issue now is it hangs at the BIOS screen so I guess that means 2 non-working motherboards. Ugh.
I think I'll just make life a lot easier and put a socket 7 board in there

Well, that's a major butt... Mine did that when I had IDE devices it didn't like. I ended up with the CF on one channel and the CD on another - does your sound card have an IDE interface?

Sound card does, tried to boot with the IDE + Floppy + HD disconnected, same thing.

Also I found out the old GW2000 mobo boots if there is no keyboard but if I plug it in and turn it on, I get that awful beep. Weird.

Your keyboard is an AT one, right, not XT? Ruling out the easy possibility before suggesting the possibility of a board suffering from squirrelly caps. I've got a K6 machine that's thoroughly out of action due to that right now.

Both boards have PS/2 keyboard/mouse ports onboard and no AT connector

Oh, so much the better. Mine's got an AT keyboard port and has to use a serial mouse; I'd forgotten that some of them used PS/2. Well, so much for the easy possibility, alas 🙁

Thanks jade_angel and everyone else for the help. Since I have a working PSU, RAM, network card, sound card, HD, CD, floppy, and COAST modules I think I'll hunt for a socket 7 AT board. I'd just need an AT to PS/2 connector, a PCI graphics card and a mobo with a processor + heatsink.

I do have a spare AMD K6-2/475 floating around if you manage to find a Super Socket 7 board (and some AT examples did exist, I think, though the one I have is ATX). I've got a PCI Matrox G550 that I could spare too, but it's got a low-profile bracket, which is probably none too helpful.

Ordred an FIC PT-2003 or PT-2000 with a 133MHz Pentium in it. Cheapest working Socket 7 combo I found on eBay. Also got a Matrox Mystique 220 for it.

Got the motherboard in the mail today. It's an FIC PT-2003.

Pictures http://imgur.com/a/LUFcg

Came with 80MB RAM (2x32 + 2x8MB), a 256K COAST module, and a 133MHz Pentium processor. Had to replace the CMOS battery.

Fits into the case perfectly. Reused the ribbon cables that originally came with the GW2K. Using a DIAMOND STEALTH 3D 2000 pro 4MB PCI video card for now (ordered a Matrox Mystique, might use that instead when it comes). 3COM 3C905-TX PCI ethernet and a Yamaha YMF719 sound card. Replaced the proprietary 2X Sony CDROM drive with an IBM 40X CDROM drive. The hard drive is a 426MB Conner. Everything works fine! When I get home from work I'll get to installing MS-DOS + WfW 3.11

It's all done now. There's nothing Gateway about this, except for the floppy drive, case and PC speaker. Reused the case and here are the rest of the specs

FIC PT-2003 Socket 7 Motherboard

Pentium 133MHz (just like the Gateway 2000 I grew up with)

64MB SIMM RAM

3.5" floppy drive

40X IBM CDROM

420MB Conner 3600RPM hard drive

MS-DOS 6.22 + Windows for Workgroups 3.11

Matrox Mystique 220 4MB PCI video card

YAMAHA Audician32 YMF-719 S ISA sound card

3COM 3C905-TX PCI ethernet card

Serial port card for my serial trackball (the original serial ports designed for a Gateway 2000/Micronics 486 board uses different pinouts)
Pictures http://imgur.com/a/Pmhl0

Very nice setup, a fairly classic setup. I really rather like the Yamaha sound card too (grab a Dreamblaster S2/X2 for it if you want some General MIDI sweetness).

I rather like that keyboard, too - one of the best rubber dome keyboards made, right up there with the Sun Type 5/7 and the SGI Granite.

Thanks! It's a very nice keyboard to type on. The newer Lenovo Preferred Pro ones aren't as good but they're quite similar.

One thing I had issues with is the softsynth caused a "Not enough memory to run Windows" error so I had to go into SYSTEM.INI and remove the DEVICE=VSGM.386 line. Go to the Yamaha line and change the 0's to 1's for these

[Yamaha]
CPLMPUBoth=1
DelSoftSynth=1

Oh, hey, thanks for finding the solution to that! Mine had that issue too, and I couldn't come up with a fix!

I'll make a post about the issue on the sound section of Marvin.

Also here's the AUTOEXEC.BAT, CONFIG.SYS, and output of mem /c

https://pastebin.com/RLv6UeFq