Asus boards are absolute assholes about needing a CMOS battery with decent voltage to work and can play dead with batteries other boards wouldn't even be losing time on yet.

BitWrangler wrote on 2023-11-07, 22:27:

Asus boards are absolute assholes about needing a CMOS battery with decent voltage to work and can play dead with batteries other boards wouldn't even be losing time on yet.

Haven't tried switching the battery! Will try that tomorrow

Make sure both cmos clear and chasiss intrusion jumers are at the correct position.

On my MSI K8T Neo2 board the negative 5V rail provided by older ATX PSUs is mandatory. Using a newer ATX PSU without -5V results in no POST, no picture, dead as a stone. I've found on the net that the MSI K8N seems to have the same issue, maybe that's true for your board as well? Do you have an PSU that still has the -5V rail?

Wonder how long 3xAA batteries would last to fake a -5 if nothing is actually using it really and it just needs to measure it's there 🤣

I checked my A8n SLI and it posts fine with modern psu and without the cmos battery, I even set the jumpers to the wrong position and it still post.
also looking at the schematics for this model, psu -5v doesn't go anywhere other than a 0.1uf cap.

Damn, was worth a shot though. Took me a while to figure that out on my MSI board, so I had hoped that I could spare you the trouble.

You can try to remove everything, CPU, RAM, GPU, and everything else that is connected to the board. Then see if it turns on (connect a fan or observe the PSU fan). It won't POST of course but it should at least tell the PSU to turn on. Are all power connectors connected? Minimum is the ATX 24 pin and the 4 pin connector next to the CPU ("ATX12V"), the 4 pin Molex should only be needed for SLI setups. Also check that you are bridging the correct pins on the front panel header. That has happened to me numerous times before, no offense.

If it doesn't turn on at all in that configuration, something is wrong with the board. If it turns on but shuts off immediately, there's likely a problem with the power supply, a short circuit for example. Not necessarily with the PSU itself, it can be something on the board, shorted capacitor, blown MOSFET. If it does turn on, you can slowly start adding components back and see when it stops working.

Tried replacing the CMOS battery, but unfortunately still no post. I'll strip the board down and I'll try to connect everything step-by-step. Will update! Thanks for the help so far.

bassix6 wrote on 2023-11-13, 10:53:

Tried replacing the CMOS battery, but unfortunately still no post. I'll strip the board down and I'll try to connect everything step-by-step. Will update! Thanks for the help so far.

FWIW, I pick up allot XP era stuff at estate sales and what not. No exaggeration when I say that at least 50% of it will just be dead. Idk if it’s because of the capacitor issues of that era, or just how they were building things in the 2000’s but boards of that era are just not reliable at all.

Heck I remember living it through that time and everything, Xbox 360’s, graphics cards, motherboards, everything was just crap 🤣. So don’t rule out the possibility that it’s just dead.

Have you multimeter tested the power supply or tested it with another board to rule that out?

I think this A8N and my other one are busted. Stripped them both completely down and tried two different PSU's, that are known to be working in other builds. The fan of the PSU quickly turns on, but immediately stops. I think I'll have to look for another board for my Athlon 3500+

If you can, try recapping it. I've replaced 100s of caps that look even perfectly fine and tested okay this year alone but once I did any issues I was having immediately disappeared. I'm finding more and more that a visual inspections of capacitors is no longer good enough. Everything's going to eventually need to be capped one day anyways.

Yeah, I also had a dead board with good looking caps but caps went bad. Can be the issue indeed

Wasn't this board somewhat notorious for having the chipset fan die without warning or notice and contributing to the boards eventual death ?

bassix6 wrote on 2023-11-13, 18:47:

I think this A8N and my other one are busted. Stripped them both completely down and tried two different PSU's, that are known to be working in other builds. The fan of the PSU quickly turns on, but immediately stops. I think I'll have to look for another board for my Athlon 3500+

If you have a multimeter, check the resistance between this inductor and ground:

technokater wrote on 2023-11-08, 13:00:

On my MSI K8T Neo2 board the negative 5V rail provided by older ATX PSUs is mandatory. Using a newer ATX PSU without -5V results in no POST, no picture, dead as a stone. I've found on the net that the MSI K8N seems to have the same issue, maybe that's true for your board as well? Do you have an PSU that still has the -5V rail?

That's interesting info..... this applyes to P4VP-MX also?

BitWrangler wrote on 2023-11-07, 22:27:

Asus boards are absolute assholes about needing a CMOS battery with decent voltage to work and can play dead with batteries other boards wouldn't even be losing time on yet.

Have about 30 Asus motherboards between 2000-2010 year range. Not single one did this, every one started without battery, just good.
Have Asus A8n-sli premium too, board starts normally withou battery. 😀

bassix6 wrote on 2023-11-13, 18:47:

I think this A8N and my other one are busted. Stripped them both completely down and tried two different PSU's, that are known to be working in other builds. The fan of the PSU quickly turns on, but immediately stops. I think I'll have to look for another board for my Athlon 3500+

You have probably short somewhere on board. Can be bad cap, can be burned MOSFET, or other component.
PSU tries to start, but immidiatelly shuts down, after it detects short... that mean, PSU start to draw too much power on one rail, PSU immidiately turn off to prevent burning.

W.x. wrote on 2023-11-14, 14:38:

BitWrangler wrote on 2023-11-07, 22:27:

Asus boards are absolute assholes about needing a CMOS battery with decent voltage to work and can play dead with batteries other boards wouldn't even be losing time on yet.

Have about 30 Asus motherboards between 2000-2010 year range. Not single one did this, every one started without battery, just good.
Have Asus A8n-sli premium too, board starts normally withou battery. 😀

Maybe it's a failure mode, have had P2B and A7V that did it for sure. If you tested that with the PSU plugged in without draining the caps though, you didn't test it.

darry wrote on 2023-11-14, 09:11:

Wasn't this board somewhat notorious for having the chipset fan die without warning or notice and contributing to the boards eventual death ?

It depends on the board. I have the same board and it’s passively cooled. Some of them did have little fans though, and yes those always die eventually and cause over heating.