Weird. I know it's low hanging fruit, but have you tried different RAM?

Last picture, on the right of the CPU: There should be a MIC29302BT voltage controller. If it were the full retail product that actually supports those 100 MHz DX4 chips as advertised on the board around the corner. Well, hence the disclaimer on page 2 of that PDF - they sold budget edition of it with the same marking about 100 MHz despite lacking that very feature.
Alas - none of the CPUs needs 3.3 V and that would not fit the problem anyway.
Also in said picture: Jumper JP30 for "write back" cache is closed but IIRC, all the "vanilla" 486 were write-through, hence that jumper should be open.

Still, weird problem and probably unrelated.

Think I remember that "100 MHz" writing and might actually have the same board, back on the heap. Very unlikely, but might be able to compare certain aspects.
In any case, good luck!

For the ram, yes I've tried many different sticks of sizes and brands

JP30 I have tried with and without on the different settings I've used, but you gave me an idea with the voltage controller.
Maybe it cant go past 16mhz because not enough voltage is supplied? When i get home ill do some poking around to see if that's the case.

Thank y'all for the help so far.

Nope, that voltage controller was merely a general remark.
All CPUs you mentioned should be 5 V most likely, the DX-33 for sure. And the board without the regulator will provide just that.
So, all that could go wrong with that is frying a 3,3 V CPU but your's are not.
No explanation for the malfunctions you're experiencing, sorry.

You can of course figure out which pin of the socket should provide those 5 V to the CPu and measure that with a voltmeter - as good a stab in the dark as many.

Is the board by any chance running in deturbo mode? CPU detection might be confused when starting deturbo'd?

MX chip next to a crystal is responsible for generating clocks, being stuck at 16MHz is a weird defect, maybe something is corroded near it

NuKaSLaYa wrote on 2022-03-22, 14:25:

....... […]
Show full quote

.......

I've tried 3 different processors
Intel 486 DX at 33mhz
Intel 486 DX2 at 66mhz
Cyrix CX486 DX2 at 50mhz

I've even taken the zif socket apart and cleaned all the pins

Other notes:
JP5, 6 and 7 control the speed but nothing will post without jumper 7 shorted, even if the setting doesn't call for it.

........

Not sure, but:
As you already wrote, JP5, 6, 7 control the external frequency.
How did you set it?

on the picture I see JP5, JP6, JP7 ON, OFF, OFF which means 50MHz.
That is wrong, you should set 25 MHz of course.
I also do not understand your "but nothing will post without jumper 7 shorted". The only documented setting where JP 7 is OFF is the 50MHz. You don't have a CPU with 50MHz externally.

So try again with a DX33 and ON, ON, ON. Or did you do that already? Or the DX2-50 with external 25MHz, that one won't run on 33MHz most likely.

Doornkaat wrote on 2022-03-22, 20:34:

Is the board by any chance running in deturbo mode? CPU detection might be confused when starting deturbo'd?

good point - you may need to short the J3 header for "turbo switch" with a random jumper to enable the faster mode. Or it's the other way around - it never got standardized, IIRC.

Cuttoon wrote on 2022-03-22, 20:49:

Doornkaat wrote on 2022-03-22, 20:34:

Is the board by any chance running in deturbo mode? CPU detection might be confused when starting deturbo'd?

good point - you may need to short the J3 header for "turbo switch" with a random jumper to enable the faster mode. Or it's the other way around - it never got standardized, IIRC.

True, I did not see that.

As far as I see in the picture, you let J3 open
That is undefined 😁, you should set a jumper to 2-3 for Turbo. Or to 1-2 for non Turbo.

So set JP5, JP6, JP7 and J3 correctly, please

Finally home and able to test more.
It's set for 50mhz right now since the cyrix is in. I assume the cyrix dx2 50 runs at 50mhz?
I've tried all 3 with the correct settings but as for my jumper 7 here's an example..
If said processor needs jumper 7 shorted in it's config then it will post, but if any processor requiring let's say 5 and 6 or just 5 shorted it won't post at all. Only configs that involve jumper 7 work. The cyrix dx2 requires only jumper 5 (assuming it's 50mhz) and will not post, If I switch it to jumper 7 for testing purposes then it posts but has the same issue as the rest, detecting it as a 80386dx at 16mhz.

I also forgot to add that I have not gotten past post, it hangs with the cursor blinking continuously, I only got into the bios once and it run super slow.

Removed jp30 to see if that had any effect, no dice.

I do have a bag of spare crystals, so I could try replacing it. Assuming I have the correct one on hand.

As for the turbo switch, 🤣 I can say that indeed gave me different results... I'm starting to think something is horribly wrong with this board.

Please excuse the dirty screen, it's my test area.

Come on, man.

a DX2 doubles the clock.
So a DX2/50 needs 25MHz.
a DX2/66 needs 33MHz.

I start to think, that you find an undocumented setting and really set the frequency to 16MHz. Combined with Turbo off, that is really slow.

CoffeeOne wrote on 2022-03-22, 23:12:

a DX2 doubles the clock.
So a DX2/50 needs 25MHz.
a DX2/66 needs 33MHz.

What he said. There actually is a pretty rare "486 DX/50" chip for 50 MHz FSB, but the thing is, that isn't a DX2. Also, only from Intel, IIRC.

So, first go through all the jumpers in the manual and double check their setting and google those you're not 100 % sure of what they do. The board does work, after all.

There's not too much information value in that photo of the screen since these low level bios messages tend to have weird display on LCD sometimes.

CoffeeOne Yeah, dang.. i did miss that with the dx2/50 I've been swapping them so much i must have got confused. like i said i could be missing something embarrassing, so no need to get testy with me.

I wish i could say that was the issue but it wasn't, so i probably had it right the times before when i did it.

Right now i have the 486 dx2 66mhz in, jumpers set to 33mhz and turbo on the right setting, still seeing it as a 386.

I've dealt with many 486 boards in the past so this isn't my first rodeo, some were in worse shape then this one but I've never had one get stuck like this, as to why I reached out for help

Yep, sorry, maybe your board is just malfunctioning in a really weird way, no matter what. 🙁
As the saying goes, horses have been seen to vomit, huh?
Good luck anyways! 😉

I actually wasn't aware of that Cuttoon, ill try in on a crt after i do some trace following to make sure i didn't miss any battery damage. Thank you.

Ha, yeah its been in a hot Texas shed for years so hard to tell what else went bad on it. might be time to put this horse down. But i do really appreciate all the help, Thanks guys

NuKaSLaYa wrote on 2022-03-22, 23:36:

I actually wasn't aware of that Cuttoon, ill try in on a crt after i do some trace following to make sure i didn't miss any battery damage. Thank you.

Ha, yeah its been in a hot Texas shed for years so hard to tell what else went bad on it. might be time to put this horse down. But i do really appreciate all the help, Thanks guys

I would suggest that you make more tests with the plain normal 5volts DX-33 MHz. So 33MHz.
So remove all settings for Cyrix ....
also remove settings for P24D and so on ...... no jumpers on JP24
Just to double check.
I think the board has no 3.3 volts support. Is your DX2-66 a 5volts or a 3V variant?
But repeat all the tests with the DX-33. Before you start investigating about replacing something. Just a suggestion.

Finally found out what the issue was.
Just in case someone else has this issue, try flashing the bios again.

I put this off till the very end because it required me to take the rom out and flashing it with a programer that I had to hunt for 😒 I read and saved the original bios file and compared it to the one I found online, same version but they were different when compared. Flashed the one I found online to a new rom and boom! Works now and displays the right processor. This would also explain why it was running extremely slow and was hanging on post.

It seems this hardware is getting so old now that nothing can be taken for granted. Can't even trust ROMs to hold their bits anymore. 😀