In my opinion, you could already try the DX40, without changing anything, then if it works, and it almost certainly will, you could check in the bios, if it has options for the ISA slot frequency, in particular there should be a 1/5 divider, if there is I think you can start looking for an 80 MHz quartz, which would replace the one present in the 66.6MHz MB

PC@LIVE wrote on 2024-09-28, 20:36:

In my opinion, you could already try the DX40, without changing anything, then if it works, and it almost certainly will, you could check in the bios, if it has options for the ISA slot frequency, in particular there should be a 1/5 divider, if there is I think you can start looking for an 80 MHz quartz, which would replace the one present in the 66.6MHz MB

there is no quartz besides a 14mhz one, and a PLCC onboard thats whats confusing me

Hmm is this your board: https://theretroweb.com/motherboard/image/pcc … 6a440710022.jpg ?
Yes some of the M321 have a crystal and some have a clock gen ic, an Av9107 or equal. There are 4 frequency available 40, 50, 66 and 80mhz from the IC. Depending on jumper settings (there is one right next to clock).
Cannot find a manual with that jumper setting...try. jumping 1-2 and boot up, and then 2-3 and see what happens in each position.

Horun wrote on 2024-09-28, 21:42:

Hmm is this your board: https://theretroweb.com/motherboard/image/pcc … 6a440710022.jpg ?
Yes some of the M321 have a crystal and some have a clock gen ic, an Av9107 or equal. There are 4 frequency available 40, 50, 66 and 80mhz from the IC. Depending on jumper settings (there is one right next to clock).
Cannot find a manual with that jumper setting...try. jumping 1-2 and boot up, and then 2-3 and see what happens in each position.

yes thats identical to my board almost, ive got all the cache sockets on mine, and yes J16 chooses between 33 and 40mhz, and im gonna test with it off and im guessing thats 25

So for anyone looking

1-2 is 40mhz, 2-3 is 33mhz and off is 25mhz

Good work. Maybe you can map put that jumper setting...

Horun wrote on 2024-09-29, 04:48:

Good work. Maybe you can map put that jumper setting...

Not sure what you mean, but I submitted it to the Retroweb if anyone else comes across this

candle_86 wrote on 2024-09-28, 21:01:

PC@LIVE wrote on 2024-09-28, 20:36:

In my opinion, you could already try the DX40, without changing anything, then if it works, and it almost certainly will, you could check in the bios, if it has options for the ISA slot frequency, in particular there should be a 1/5 divider, if there is I think you can start looking for an 80 MHz quartz, which would replace the one present in the 66.6MHz MB

there is no quartz besides a 14mhz one, and a PLCC onboard thats whats confusing me

I saw in the following messages that you solved it, I honestly thought you had the model with quartz, but that's not the case.
I did a short search online, and I found images of a MB very similar to yours, without quartz, I'll put the images here, maybe they can be useful to someone, but could you tell if it corresponds to your MB?
Unfortunately, not having an identical MB, I cannot take photos of details, the quartz or jumper area can be seen in the photo of the MB (zooming in).

yea its like mine, its kinda cool to have a 386 board with a clockgenator

I love the 386, I don't have many, a 386 SX33, and two 386 DX40, I like them because my first PC was a 386 DX33, I sold it years later to buy a 486 DX2-66, being able to go back, I would have kept it, but that's the only one I sold, I have all the following ones in my collection, except a 486 DX4-100 that they threw away without my knowledge.