Check PSU voltages (without it connected to the motherboard).

Remove CPU, check voltages. Test the different components in a different mobo (CPU, RAM, VGA). Check CMOS-battery voltage.

Check for an FSB (can't recall the pin)

I had an Epox VP3 that crapped it's 3,3V rail when the PWM-controlled died. Pushed 5V *everywhere* where it should not be. That board became spares ...
Also killed the CPU, no surprise here.

Do you have an POST card? If yes, insert it to an PCI slot and post here what it says.

no beeps and boops? try without ram and graphic card, just mobo cpu and supply

Thanks for all replys and suggestions!
I think the standalone components are working and that is something with the power on the motherboard. When I connect the PSU to an outlet, the PSU immediately starts up and the CPU fan starts as well, before I use the power switch button connected to the motherboard. But no beep, and nothing more happens, only spinning fans from PSU and CPU fan.
Tried out with another PSU, and got the same result.
Any thoughts why that happen?

Also, pressing the power switch button for the motherboard once the fans started spinning does not turn them off. Only way to turn them off is to turn off the PSU.

sadly no diagram/boardview available for this board
PSU is sadly controlled directly by PIIX4 (southbridge), there is a slight chance board generates its own 3.3V and its bad, another option is Power button signal being buffered with a transistor that died, all in all you need to measure some voltages and trace atx power on pin

rasz_pl wrote on 2024-04-27, 14:37:

sadly no diagram/boardview available for this board
PSU is sadly controlled directly by PIIX4 (southbridge), there is a slight chance board generates its own 3.3V and its bad, another option is Power button signal being buffered with a transistor that died, all in all you need to measure some voltages and trace atx power on pin

Thanks for detailed explanation!
These things are a bit more complex than what I am used to handle, but sounds like very likely causes.
So if it is any of those two (bad 3,3v generation or bad transistor), is there any simple way of fixing /replacing them?

I see a broken cap next to the CPU socket.

Using these pictures as reference:
http://hw-museum.cz/mb/101/asus-tx97-xe

Q8 might be a 3.3V regulator (with Q9 used to connect 3.3V to the CPU core supply if an old single-rail CPU is installed), but it's hard to tell with only some pictures. However, that's a small FET without much cooling, so I think it's more likely that 3.3V is coming directly from the power supply. The CPU voltage should be on the inductor next to the RAM slots (L6?). You might see something if you measure the voltage on all three pins of Q8 and Q9 along with the inductors (L15 should be connected to 5V). Note that Q1 is actually a diode, and the two pins close to the board edge should connect to ground.

Also, what CPU do you have installed, and what are the Vcore jumpers set to? That's a reference point for whether the voltage readings above are correct.

Coincidentally, I have a different model of motherboard with the same chipset and the same symptoms. I haven't tried to fix it yet because I don't have a spare power supply.

lti wrote on 2024-04-29, 04:17:

I see a broken cap next to the CPU socket. […]
Show full quote

I see a broken cap next to the CPU socket.

Using these pictures as reference:
http://hw-museum.cz/mb/101/asus-tx97-xe

Q8 might be a 3.3V regulator (with Q9 used to connect 3.3V to the CPU core supply if an old single-rail CPU is installed), but it's hard to tell with only some pictures. However, that's a small FET without much cooling, so I think it's more likely that 3.3V is coming directly from the power supply. The CPU voltage should be on the inductor next to the RAM slots (L6?). You might see something if you measure the voltage on all three pins of Q8 and Q9 along with the inductors (L15 should be connected to 5V). Note that Q1 is actually a diode, and the two pins close to the board edge should connect to ground.

Also, what CPU do you have installed, and what are the Vcore jumpers set to? That's a reference point for whether the voltage readings above are correct.

Coincidentally, I have a different model of motherboard with the same chipset and the same symptoms. I haven't tried to fix it yet because I don't have a spare power supply.

Ok! Do you mean this one?
I thought this was just bent, but perhaps that indicates that it is broken?

At that angle, it looks like one lead is ripped out. That might not be the only problem with this board, though.

lti wrote on 2024-05-01, 04:09:

At that angle, it looks like one lead is ripped out. That might not be the only problem with this board, though.

I see… I don’t even have a multimeter so not sure if I wanna go down the road and troubleshoot each pin/connection 😀
Replacing a capacitor I could try out, sounds like quite doable.. but as you say, might not end there.
Really appreciate all your input and thoughts, though!
I might reconsider and revisit this as a project 😀