Have you tried with another power supply?
If you have a multimeter handy, check resistance between each rail and ground, looking for shorts. Anything below tens of ohms is suspicious.
Also, is there a possibility that the board was made for Dell? If so, the ATX pinout is non-standard.

Careful. Look for the Dell part number first.

The dallas battery backed modules needs to be modified with external battery first as some oddball boards refuses to boot with exhausted battery in them.

Cheers,

CR2032 cmos battery can be dead. Check it or just swap to fresh one.

Shame 🙁 - I'm working on my two atm, an Intel retail and a Packard Bell OEM (PB885) - both rev 2 with AGP x2. They're nice boards so hope you get it fixed.

Apart from the suggestion of a fresh coin cell battery / cmos clear the only other thing I can think of is a bad flash - have you ever had the board working? There are completely different versions for revs 1 & 2 so not sure what would happen if the wrong one was used (forced recovery flash?). Is it an Intel or PB version (not aware of a Dell one).

hi guys i hope you can help with the part number

so i changed the coin battery as you mentioned and that did not help at all. I am sure the PSU is not the issue, because i always use it every week

on the white sticker i see this part number:

IUMU83201918 AA 718631-405

does that mean that it needs some kind of special power supply? or it should work with any atx power supply,?

because if it needs a modified one. it woukd explain why the psu fan does not even spin.

the bios chip is pretty small intel flash for that era. where bios were bigger, but this one is really thin and small

That's exactly the same AA number as my on Intel retail, so it's a definitely a rev 2 with AGP x2 and no, it doesn't need a special PSU - I'm currently using a old 200W 20-pin ATX.

I've got an Intel PPro board that won't power up when the switch is pressed. Only way to get it to power is to short the green PSU wire to ground. After that it seams the board will power on and off with the power button. From what I can tell, the motherboard thinks its on when off and vice versa, so pressing the power button when off tries to turn it off. Forcing it on seams to reset things. Got another dual Xeon board that I shorted the 5VSB, that only powers up via the green-to-ground PSU forced start-up method. Maybe worth a try?

I have a MU440EX rev 1 and it would only boot from a 266 or 300Mhz cpu when I first got it due to it still had the original BIOS version 4M4UE0X1-403. What speed CPU are you trying to boot from ?

mR_Slug wrote on 2020-05-11, 23:21:

I've got an Intel PPro board that won't power up when the switch is pressed. Only way to get it to power is to short the green PSU wire to ground. After that it seams the board will power on and off with the power button. From what I can tell, the motherboard thinks its on when off and vice versa, so pressing the power button when off tries to turn it off. Forcing it on seams to reset things. Got another dual Xeon board that I shorted the 5VSB, that only powers up via the green-to-ground PSU forced start-up method. Maybe worth a try?

Sounds like your PPro board could be an OEM or the PSU is. Some boards the power-on was taken low, others taken high. Same with some PSU (I know Mac psu are opposite of PC that way)....

Horun wrote on 2020-05-11, 23:36:

I have a MU440EX rev 1 and it would only boot from a 266 or 300Mhz cpu when I first got it due to it still had the original BIOS version 4M4UE0X1-403. What speed CPU are you trying to boot from ?

Suppose it could be some issue with the cpu but I doubt it. The OPs board has an AA number which identifies it as rev 2, and although according to Intel the broadest official cpu support starts at 4M4UE0X3.86A.0004.P03

here's my board booting a Celeron 533 PPGA on a slocket with the original production release bios for rev 2 boards (ignore the 500MHz string - even with the latest bios the POST screen doesn't recognise anything above 66MHz x 7.5, beyond that everything else sees a Celeron 533)

In fact, the production release notes hardly mention processor support / fixes at all

i gave it a last try, i was hoping that i needed a propietary power supply as my last hope, but if it has to work on any atx power supply...then im out of luck

tried with pentium2 266, and also pentium2 300, and nothing works, not even the cpu fan spins ,nor psu fan
touching pin6 and 8 does absolutly nothing , and the intel flash chip is just to small to take it out and read it with a bios reader tool and flash it.

what a pain, might go to the trash bin

Cga.8086 wrote on 2020-05-12, 04:20:

what a pain, might go to the trash bin

"If you have a multimeter handy, check resistance between each rail and ground, looking for shorts. Anything below tens of ohms is suspicious."
Did you do this?
Also replace these:

What brand/model/date code are those caps near the CPU? I know even a Japanese brand had a bad series at some time.

If its anything like mine, they're United Chemi-Con LXZ series 2200uF/16V. On the other hand the PB version uses Panasonic FC series 2200uF/16V. By comparing chip dates I'd say my boards were made within a month or two of each other around late 98 / early 99. Visually they're all in excellent condition for their age (yes, I know looks can be deceiving 😀 )

Cga.8086 wrote on 2020-05-12, 04:20:

i gave it a last try, i was hoping that i needed a propietary power supply as my last hope, but if it has to work on any atx pow […]
Show full quote

i gave it a last try, i was hoping that i needed a propietary power supply as my last hope, but if it has to work on any atx power supply...then im out of luck

tried with pentium2 266, and also pentium2 300, and nothing works, not even the cpu fan spins ,nor psu fan
touching pin6 and 8 does absolutly nothing , and the intel flash chip is just to small to take it out and read it with a bios reader tool and flash it.

what a pain, might go to the trash bin

If nothing happens when you touch the power switch pins, it means there is something seriously wrong with the southbridge (usually it's fried). You can't do anything about it in that case. (unless the CMOS clear jumper is not set properly, some boards wil refuse to power on if not)

There is no point in flashing another BIOS if the standby circuitry is malfunctional.

Already confirmed the jumper was set to Normal

I'd be more inclined to suspect a bad flash (either a failed chip or borked in a bad flash upgrade) - that's why I dislike these Intel bios chips.

PC Hoarder Patrol wrote on 2020-05-12, 10:26:

Already confirmed the jumper was set to Normal

I failed to notice that, my bad 😉

I don't think a failed flash should cause the board not to power on at all. At least, I haven't heard of a failure like that yet.

When I had power on issues with salvage boards (P4P800-SEs in particular), I could usually feel a ton of heat coming from the southbridge in seconds (it would burn my finger).

Horun wrote on 2020-05-11, 23:39:

...Sounds like your PPro board could be an OEM or the PSU is. Some boards the power-on was taken low, others taken high. ....

Just Illustrating a method of starting a motherboard. I think it's referred to as the Paper-Clip method. Should point out this is only recommended when everything else has been checked/tried. Short pin 14 (/PS_ON), Green to ground. You have to leave the paper-clip in, its not momentary, like the jumper on the motherboard. If you're about to trash the board, its worth a try.

Cga.8086 wrote on 2020-05-12, 04:20:

i gave it a last try, i was hoping that i needed a propietary power supply as my last hope, but if it has to work on any atx power supply...then im out of luck
what a pain, might go to the trash bin
***

Cga.8086, it's too early to give up. Although you're sure that the PSU is OK try another one anyway. This mainboard is picky about PSU.
P.S. There's a way to turn the motherboard on but I haven't tried it yet. The motherboard has WOL connector near CMOS-bat. The method is to connect the #1 and #3 pins through a 1-5kOm resistor instantly.