Tested the board with an bequiet PSU but still same issue. After shorting ps_on with ground pins on the hp power supply, it turns on for a second then dies. Any ideas?

Bumping this thread.

No experience with that model, but the "screeching noise" is some feature of the way too many under the name of "HP e-diagtools", its point is that you could call HP, stick your phone up to the PC Speaker, and have their software decode a more detailed error 😀

You should be able to force that sound on a working system by turning it on and hooding the power button - which AFAIK is the only legitimate reason to have that followed by no conventional beeps at all 😀 🙁

For whatever it's worth my VL400 does have a bicolor power LED, but the only thing the red is used for is to make yellow when you turn it on, it never becomes red or yellow at other times, including when making any sort of error sound…

Ryccardo wrote on 2024-05-15, 11:46:

No experience with that model, but the "screeching noise" is some feature of the way too many under the name of "HP e-diagtools", its point is that you could call HP, stick your phone up to the PC Speaker, and have their software decode a more detailed error 😀

Problem is the "screeching noise" is coming form the mainboard directly around the VRM arena, not from buzzer and speaker.

The board is closer to working condition, but not quite yet. I can get it to turn on, but it emits weird sound, almost like an dried up capacitor trying to work and sand falling onto the ground. The CPU is stuck in reset. Any ideas?

I've heared screeching noise before, but it came from the PSU as a result of a short in the PSU, causing it to continuously power-cycle at high frequency (hence the noise). So probably there is a short somewhere on the mobo in your case.

wbahnassi wrote on 2024-07-08, 09:42:

I've heared screeching noise before, but it came from the PSU as a result of a short in the PSU, causing it to continuously power-cycle at high frequency (hence the noise). So probably there is a short somewhere on the mobo in your case.

Thanks for the reply. 5V rail has 15 ohms, so I think that is a short, but I have no idea where to start troubleshooting from here. This might be a little off topic, but do you using a tooth brush to get off the fire extinguisher dust with distilled water will cause any damage?

You can wash the entire mobo with dishwashing liquid and water, scrub it with a light brush, then rinse it very well then dry it very well (either under the sun for 2 days or with an air blower). This guy does it often:
https://youtu.be/XxYga5vVgZ0?t=12m59s

As was suggested earlier, first clean the board so there won't be any 2nd guesses as to whether the fire extiguisher compound or other contaminants are messing with the board.

2nd, post some pictures of the motherboard in question. I like to see what you are seeing. You said you replaced 4x 1000 uF caps - which caps? On the motherboard? If on the motherboard, there's a high chance there are more bad caps, even if they all look good. Same applies with the PSU. On that note, has the PSU been tested with another motherboard to verify its function? If not, that could be the culprit too. Dirty power can cause motherboard VRM circuits to misbehave (and make noise) in many strange ways. Likewise, bad caps on a motherboard can also do the same to make it seem as if the issue was with the PSU.

So in short, you basically have two pieces of hardware with questionable working status and you're asking if anyone can pinpoint an exact issue for you. Chances are slim, if any.

momaka wrote on 2024-07-11, 21:49:

As was suggested earlier, first clean the board so there won't be any 2nd guesses as to whether the fire extiguisher compound or other contaminants are messing with the board.

2nd, post some pictures of the motherboard in question. I like to see what you are seeing. You said you replaced 4x 1000 uF caps - which caps? On the motherboard? If on the motherboard, there's a high chance there are more bad caps, even if they all look good. Same applies with the PSU. On that note, has the PSU been tested with another motherboard to verify its function? If not, that could be the culprit too. Dirty power can cause motherboard VRM circuits to misbehave (and make noise) in many strange ways. Likewise, bad caps on a motherboard can also do the same to make it seem as if the issue was with the PSU.

So in short, you basically have two pieces of hardware with questionable working status and you're asking if anyone can pinpoint an exact issue for you. Chances are slim, if any.

Will post the pictures of the board after it dries out and see if there's any changes in behavior. I forgot to post that the PSU was shutting down after a second. Then it started to trip breakers, but after dismantling, the short was gone. Was worried that the 2 pin connector was something propriety, but it turns out it was fan control, so for now I'm putting it aside. For testing purposes I'm using an standard ATX PSU. The mainboard is ASUS P4SD rev 1.09, according to prints on it.

The board dried off faster than I expected, but just to be safe I'll let it sit for a couple of days in the sun. Attaching pictures of it. I've replaced the 1000uF caps on the mainboard next to PCI slots and AGP.

Ah, the P4SD, I know that one pretty well. It was one of my first commercial recap jobs. I have an entire thread dedicated to it here:
https://www.badcaps.net/forum/troubleshooting … erboard-polymod

That said, you might want to further replace some of the caps on yours.
The CPU VRM low-side area looks good - I see all Panasonic FL electros and Sanyo SEPC polymers. All of these can stay and are good.
However, all of the Teapo caps need to go. The three 16V 1200 uF ones a little further from the CPU should be changed. Panasonic FM or FR or FS or Nichicon HW or HV or United Chemicon KZE or KZH or KZM or Rubycon ZL or ZLH or ZLK should all do the job fine. While at it, grab an extra one and fill-in that empty spot too. You can use either 1000 uF or 1200 uF or 1500 uF caps (@ 16V rating) - the board won't care.
I suspect the "whistling" noise you're hearing is from the NB VRM filter caps. That would be, IIRC, rail "F" on my cap map on the BCN drawing I posted. It's comprised of two Teapo 6.3V 1000 uF caps close (under) the 4-pin 12V CPU connector shown on your picture here.
It looks like you also have two Nichicon HM series capacitors on the Vdimm (RAM supply) rail. This one is labeled "C" on my diagram. It's in parallel with the Rubycon MBZ 6.3V 3300 uF cap below them, so even if they are bad, the board can still typically "limp" with that.... but it's recommended you replace those two Nichicon HM caps if they have a date code with a range of H01xx through H05xx. They often go bad, but don't always show it.

Lastly, I'm assuming you removed the Northbridge heatsink just for when you were washing the board and didn't try running the board like this. Granted the i865 is a pretty tough chipset, but you still need to run it with its proper heatsink nonetheless.

kotel wrote on 2024-07-08, 10:42:

5V rail has 15 ohms, so I think that is a short

https://www.calculator.net/ohms-law-calculator.html

P4 HP from right in the middle of capacitor plague means you replace ALL caps (if you for some reason decide not to throw it away immediately), not just the ones that look bad

Powered on the mainboard today and the screeching noise on startup disappeared, but its back to 3 blinks followed by 4 blinks which goes forever.

momaka wrote on 2024-07-12, 22:27:

Ah, the P4SD, I know that one pretty well. It was one of my first commercial recap jobs. I have an entire thread dedicated to it […]
Show full quote

Ah, the P4SD, I know that one pretty well. It was one of my first commercial recap jobs. I have an entire thread dedicated to it here:
https://www.badcaps.net/forum/troubleshooting … erboard-polymod

That said, you might want to further replace some of the caps on yours.
The CPU VRM low-side area looks good - I see all Panasonic FL electros and Sanyo SEPC polymers. All of these can stay and are good.
However, all of the Teapo caps need to go. The three 16V 1200 uF ones a little further from the CPU should be changed. Panasonic FM or FR or FS or Nichicon HW or HV or United Chemicon KZE or KZH or KZM or Rubycon ZL or ZLH or ZLK should all do the job fine. While at it, grab an extra one and fill-in that empty spot too. You can use either 1000 uF or 1200 uF or 1500 uF caps (@ 16V rating) - the board won't care.
I suspect the "whistling" noise you're hearing is from the NB VRM filter caps. That would be, IIRC, rail "F" on my cap map on the BCN drawing I posted. It's comprised of two Teapo 6.3V 1000 uF caps close (under) the 4-pin 12V CPU connector shown on your picture here.
It looks like you also have two Nichicon HM series capacitors on the Vdimm (RAM supply) rail. This one is labeled "C" on my diagram. It's in parallel with the Rubycon MBZ 6.3V 3300 uF cap below them, so even if they are bad, the board can still typically "limp" with that.... but it's recommended you replace those two Nichicon HM caps if they have a date code with a range of H01xx through H05xx. They often go bad, but don't always show it.

Lastly, I'm assuming you removed the Northbridge heatsink just for when you were washing the board and didn't try running the board like this. Granted the i865 is a pretty tough chipset, but you still need to run it with its proper heatsink nonetheless.

Thanks for more info. Currently I only have 1000uF 16v caps that I borrow from a dead board to replace those 1200uF caps (only hit at what the manufacturer is a capital M). My Nichicon HM near RAM slots have a date code of A0345, so I guess they should be fine. Forgot to mention the 4 1000uF 6.3v (as I remember) near PCI slots and AGP were replaced with 16v caps (at the time I didn't have 6.3v ones). And yes, I removed the NB heatsink to wash the board. Ill try to replace the caps and let you know how it goes.
EDIT: Forgot to mention the board only sometimes powers on with the "whistling" noise with CPU stuck in reset.

Recaped all 1000uF and 3 of 1200uF caps with 1000uF (they are a little thinner than the TEAPO caps) but no go. If I reset CMOS, I get the "whistling" noise or 3 blinks followed by 4 blinks and 4 blinks forever after a cold boot. All of the caps I've replaced are a capital M branded (from my research it seems like they are panasonic). Any ideas?

the whistling (if loud) you are hearing is struggling DC-DC converter, either there is a short(unlikely if it blinks error codes)/low impedance somewhere or there are still bad caps

rasz_pl wrote on 2024-07-15, 23:51:

the whistling (if loud) you are hearing is struggling DC-DC converter, either there is a short(unlikely if it blinks error codes)/low impedance somewhere or there are still bad caps

I guess it will be bad caps. Currently I've replaced all of the teapo caps with panasonic ones and some luxon with KGZ (or similar brand, I know it is a bad brand, borrowed them form a dead nforce board from 2007, none seemed to leak). There are some 100uF 16v luxon caps near NB (labled D on momaka's diagram). Don't have any at hand and the same caps on the donor are also luxon, so I am not sure if to replace them with caps from the donor board. Forgot to mention, when the board decides to blink error codes, there's a quiet sound, which somewhat resembles an buzzer "clicking" The PSU does that every time it powers on. Any ideas?

Replaced the 3 100uF caps near NB and 1 3300uF 6.3v cap near RAM. All looked okay except the 3300uF one, it has leaked. Still, there are no POST codes executed and the whistling noise is still there. Desoldered both of the 1500uF caps near RAM slots and one of each type in the VRM. None had any signs of leakage. Any ideas?

You guys might find this interesting. I noticed that the speaker also emits that weird noise when MB is running. After the 3 blinks followed by 4 blinks it doesn't do anything. Not sure if I mentioned this, but when i run the board without P4 connector plugged in, the noise goes away. Even on the speaker, and the error changes from 3 blinks and 4 blinks to 3 blinks forever. But the board still shuts down after some time.... I guess it could be coil whine now? But it kinda doesn't and does make sense cause there could be so severe interference that the noise goes to the speaker.