Bet it is Bad Caps ! If you have a low end Celery try it. I had a P4 board that would not run that faster bus cpu's but would a 400 and 533. It was failing caps (higher speeds generally means more current) that could not handle the fast power hungry cpu's//

Yes could be the caps, none are bulging but they still could be going off. It's also possible I fried the CPU with inadequate Prescott cooling.
I only have a few other P4HTs and reluctant to risk them.

JayAlien wrote on 2023-02-15, 02:33:

Yes could be the caps, none are bulging but they still could be going off. It's also possible I fried the CPU with inadequate Prescott cooling.
I only have a few other P4HTs and reluctant to risk them.

Such low spirit for adventure... 🙁
Can we have a pic of the board?

Of course, I disconnected the second CPU power cable so it didn't obscure the view.

JayAlien wrote on 2023-02-15, 02:33:

Yes could be the caps, none are bulging but they still could be going off. It's also possible I fried the CPU with inadequate Prescott cooling.
I only have a few other P4HTs and reluctant to risk them.

Actually it is a bit hard to fry a P4 cpu unless it has been overclocked for a long time (something about electron migration depletion, I forget the exact term).
I still think either the board or your PSU has failed. You never said where you got the board, the cpu or how long it ran stable before this issue came up 😀

I got the board and CPU off amibay recently. It’s still on my build bench, so ‘ran stable’ for the few hours it took me to build, install win xp and get the drivers on.. maybe 3 hours?
PSU is new:

Thermaltake SMART 600W ATX 12V V2.3/EPS 12V 80 Plus Certified Active PFC Power Supply PS-SPD-0600NPCWUS-W

Thanks!

If you have a voltmeter, check the CMOS battery's voltage. If you don't (and the battery isn't brand new), try replacing it. Every now and then there is a motherboard that won't POST without a CMOS battery.

Ah I was hopeful with the CMOS battery suggestion. I've tried two batteries, one reading 3.0v and one reading 3.1v to no avail.

I don'like the looks of that cap but maybe is from the way the picture was taken. Also remove everything, but the cpu (video/ram/sound card) , connect a test card or if don't have one a pc speaker , clear cmos and power it on.

Asus P4P800 (especially the E and SE) is known for EEPROM chip / bios and some other issues. If you have an EEPROM writer, take the chip out and re-flash it. Better yet, replace the chip with a winbond of the same capacity, flashed with the correct bios. Even better, launch it off a trebuchet as posted above, and find an Abit AI7 or IS7. If you really want to stick with Asus, try sourcing an Asus P4C800, they're pretty solid.

JayAlien wrote on 2023-02-15, 02:55:

Of course, I disconnected the second CPU power cable so it didn't obscure the view.

I don't like darken lacquer near two mosfets between AGP and PCI. I think they have been very hot during long period of time. They do +1.5v voltage for chipset and AGP graphic card.
Asus often set there something like APM3055, APM3054, APM2054 that proved themselves as not so good and reliable. If they are AP9915 then it's much better.
So turn on the system and measure voltage on a pin #3 ("source", most nearest to AGP) of the top (on the photo) mosfet .
Voltage measurement should be done using a multimeter in voltage meter mode, the black tip - to GND, the red tip - to point of measurement.

I finally got some time to take another look at this motherboard today. I found a 2.8GHz Celeron in my parts box, installed it, added a random AGP card, and I was able to power the board up.
As I took out the P4 and cleaned the thermal paste off I noticed some slight discoloration on the cpu. I may put the P4 back in and give it another try. It was generating some warmth so not completely dead.

The discoloration got me to wondering; the discoloration may be due to an overheat. My cooling solution is a cheap socket 478 cooler, with a noctua fan slapped on top. Is this enough? I do have another P4 3.2 but if I've cooked one, I don't want to fry the other.

Desktop s478 pentium4's are very 'hot', especially the ones running at fsb800. Also failing caps can cause that (less power hungry cpus like celerons to post and other not), you can test the cpu on another board to see if it's stil functional, if not, you should get a better cooler, or try mobile versions if your motherboard supports them.

Horun wrote on 2023-02-15, 00:42:

Bet it is Bad Caps ! If you have a low end Celery try it. I had a P4 board that would not run that faster bus cpu's but would a 400 and 533. It was failing caps (higher speeds generally means more current) that could not handle the fast power hungry cpu's//

Agreed with this. My capacitor knowledge started with upgrading a 2.4ghz to a 2.8ghz P4 on my Soyo. Went from random sporadic issues to hard freezing once the CPU hit 100% load in Windows. Also ran into lots of minor weirdness until I replaced the secondary caps later on.

Yes, that's also why when i test a 478 board, i use 2 cpu's. I have a 3ghz P4 and if i get no post i use a 2.4ghz celeron.

Socket3 wrote on 2023-02-16, 17:09:

Asus P4P800 (especially the E and SE) is known for EEPROM chip / bios and some other issues. If you have an EEPROM writer, take the chip out and re-flash it. Better yet, replace the chip with a winbond of the same capacity, flashed with the correct bios. Even better, launch it off a trebuchet as posted above, and find an Abit AI7 or IS7. If you really want to stick with Asus, try sourcing an Asus P4C800, they're pretty solid.

Do you know why that is? Indeed i've a SE which luckily does turns on just to tell me I've a corrupt BIOS
Only PC i've had that's done it

chinny22 wrote on 2023-04-20, 09:26:

Socket3 wrote on 2023-02-16, 17:09:

Asus P4P800 (especially the E and SE) is known for EEPROM chip / bios and some other issues. If you have an EEPROM writer, take the chip out and re-flash it. Better yet, replace the chip with a winbond of the same capacity, flashed with the correct bios. Even better, launch it off a trebuchet as posted above, and find an Abit AI7 or IS7. If you really want to stick with Asus, try sourcing an Asus P4C800, they're pretty solid.

Do you know why that is? Indeed i've a SE which luckily does turns on just to tell me I've a corrupt BIOS
Only PC i've had that's done it

Corroded pins on BIOS chip very likely. I have a P4P800-E Deluxe here that needed a new BIOS chip just because the original one looked rotten as all hell.

@Socket3 - I wouldn't really rely on IS7 either. While better than the P4P800, these also had issues with their BIOS chips, from what I remember, albeit at software level (BIOS would corrupt itself, from what I remember from my BE6-II) though I wouldn't take a dying BIOS chip off the list.

The board looks nice in the photos , you may try a diffrent PSU just for testing purpouse .
You should clean the Ram slots with contact cleaner , and rams.
If it boot's , upgrade or reflash the bios with l8test version.
If you have soldering skills , mount high-er voltage main rail Cap's same uf.

I kind of doubt it's the caps as they look fine and rarely go bad on late Asus s478 boards.

In my experience BIOS (chip) issues like mentioned if the board powers on, shorted mosfet/mosfets in the CPU VRM circuit if it dosn't.

If the boards powers on and you have already replaced/reflashed the BIOS then keep the board powered on for a few hours. If it's the caps they might be persuaded to start working enough to let the board post.

Other things to try.

Another PSU like mentioned, especially if the board dosn't power on.
Other memory even if the memory used is known good.
Another video card.
Getting a POST-code card to see if there are any codes that could indicate where the issue is.