Don't try to solder a VL connector for VLB graphics cards. It has ECS local bus pinout!!!

DX2/50 should have passive cooling.
Re: PUTTING A HEATSINK WITH FAN ON A 486 DX 33 MHz

If you have active cooling, go for a DX2/66.

Your graphics card looks suboptimal in this memory configuration. 256 MB 🤣. Get one with 1 MB and at least a high-color DAC.

Your BIOS will have a limit at 504 MB, 2 GB or 8 GB.
You may use a DDO to overcome that limit.
I'd recommend to use an IDE HDD with not larger than 8.4 GB.

More informations on your board:
FX-3000 motherboard thread

Disruptor wrote on 2024-09-16, 16:14:

Your BIOS will have a limit at 504 MB, 2 GB or 8 GB.
You may use a DDO to overcome that limit.
I'd recommend to use an IDE HDD with not larger than 8.4 GB.

In addition to Disruptor's advice... the D-Link DE-220T card can easily accommodate a XTIDE Universal BIOS chip in the Boot ROM slot if you don't want to fuss with overlays for more flexible storage options.

Little aside, I actually still had my 4 original 1 MB 70 NS RAM chips from the original Compudyne back in the day. Since they didn't take up really any room, I've kept them all these years out for nostalgias sake (and the fact I paid $100 for each MB chip back then...)

Popped them into the 4 open slots and off to the races with 8 MB of memory. At least a little of the old machine lives on. 😀

MeatballB wrote on 2024-09-16, 20:31:

Little aside, I actually still had my 4 original 1 MB 70 NS RAM chips from the original Compudyne back in the day. Since they didn't take up really any room, I've kept them all these years out for nostalgias sake (and the fact I paid $100 for each MB chip back then...)

Popped them into the 4 open slots and off to the races with 8 MB of memory. At least a little of the old machine lives on. 😀

Yay!

1) Motherboard appears to not have any Cache chips. Is that a problem? Even if it isn't, should I pick up some chips?
The PC will work but will be much slower without Cache, I would upgrade but would focus on getting the PC up and running first.

2) Can I just swap out the SX33 for the DX2/50? I can tweak the jumpers, but wasn't sure if I need to worry about the Oscillator frequency.
Yes you will need to install a 50Mhz oscillator for the DX50, or install a Dx2/66 which also uses the 66Mhz one already installed.

3) Am I right with that VGA card being a Cirrus Logic with 256MB of RAM? I can't find any markings for manufacturer on the card.
If you meant 256k then you are correct it's a Cirrus Logic GD5401 Good card for a 386 or as a test card but probably worth upgrading on a 486 but give it a go first. if it plays all your games fine then no need wasting money.

4) Speaking of VGA, right now I'm just feeding the card out an old Dell VGA LCD I have. Some of the times, it works fine and I get to a BIOS screen and memory test. Other times I get nothing. No beeps/no video out/nothing. Could that be a problem with the card talking to the LCD or something else?
If you're getting no beeps, then it's the PC not the screen at fault. First step would be to take back to minimal configuration so CPU, 2 sticks of RAM, keyboard and go from that. as it's pretty low level if you don't even get to the BIOS screen.

5) I'm having some trouble deciphering how to setup that MIO card to get everything connected including a hard drive (still need one), floppy drives, and external ports. Particularly, can't seem to figure out JP3. Am I reading it right that it looks like Jumper '1' for that row is on the right instead of the left?
I'd just leave the card alone, good chance it's configured ok already, you can always trial and error one you have drives attached.
Worst case this shoes the default
https://www.computer-museum.net/docs/DFIMIO-400KF.PDF

6) Still need to get a hard drive. I do have a SATA to IDE adapter lying around somewhere. That actually be possible, or do I need to go out and grab an old ATA/40 Pin hard drive?
You can definitely use the adapter but as mentioned the maximum hard drive will be between 500MB - 8GB.
Software exists to reduce the hard drive to under this limit or to get around the limit, but again first things first I'd concentrate in getting a drive connected and spinning before considering what storage method you want to use.

Oh and 8MB is a very nice amount of RAM for a 486

On the MIO-400KF card... DFI made a TON of these back in the day with a number of revisions that each altered the jumper locations and settings during the product run.

Please follow the jumper settings for Rev F on The Retro Web - https://theretroweb.com/expansioncards/s/dfi-mio-400kf-rev-f

Thanks for all the help so far! Any suggestions on which oscillator I need and where's the best place to grab it? I see a ton of '50 mhz oscillators' on eBay/Amazon, but not 100% sure they'll work.

Oh, and secondary follow-up regarding that XTIDE Universal BIOS chip in the Boot ROM slot of the NIC. Is that something that can be purchased, or something I'd have to buy a chip and burn the ROM to? Need to do a bit more reading on the XTIDE project.

Machine is slowly coming back together. Waiting on a few more parts, like a new Oscillator crystal and CMOS battery, but does anyone know if it's still possible to find/source the drive rails for these old Compudynes? Seems to be stamped with 'AT9IO242-01', but no luck finding them in my searches.

I'm sure they're easily 3D printable, but don't have access to one, so was hoping to find something online, but basically can't find anything related to these and I was hoping to put a CD Drive in that 3rd bay.