IMHO at this point you are better off getting one of those ISA POST diagnostics cards to really diagnose the issue instead of blindly trying stuff.

alexanrs wrote:

IMHO at this point you are better off getting one of those ISA POST diagnostics cards to really diagnose the issue instead of blindly trying stuff.

Can you advice me a particular Motherboard diagnostic card?

mp10 wrote:

alexanrs wrote:

IMHO at this point you are better off getting one of those ISA POST diagnostics cards to really diagnose the issue instead of blindly trying stuff.

Can you advice me a particular Motherboard diagnostic card?

They are pretty generic and It's not a thing one buys frequently so I don't have a favorite.
--- What you have to pay attention to is what slots they fit in. ---
I would probably choose one that is ISA on one side and PCI on the other.
http://www.ebay.com/sch/i.html?_from=R40&_trk … c+Card&_sacat=0

PCBONEZ wrote:

They are pretty generic and It's not a thing one buys frequently so I don't have a favorite. --- What you have to pay attention […]
Show full quote

mp10 wrote:

alexanrs wrote:

IMHO at this point you are better off getting one of those ISA POST diagnostics cards to really diagnose the issue instead of blindly trying stuff.

Can you advice me a particular Motherboard diagnostic card?

They are pretty generic and It's not a thing one buys frequently so I don't have a favorite.
--- What you have to pay attention to is what slots they fit in. ---
I would probably choose one that is ISA on one side and PCI on the other.
http://www.ebay.com/sch/i.html?_from=R40&_trk … c+Card&_sacat=0

I am going to buy one of these cards...
What do you think about my last feedback?

mp10 wrote:

Thank you very much for you technical explanation. I tried to short the pins with a screw driver and nothing changed.

This means the switches are not the problem. And if you aren't already it's okay to use them again.

mp10 wrote:

PCBONEZ wrote:

Or a falsely locked-in reset (or switch) from the BIOS that changes state when the BIOS is reset.

What do you mean with "falsely locked-in reset from the BIOS"?

I meant that the BIOS may be sending the reset signal when it should not be because it's 'stuck' (won't change state).
That could be caused by the BIOS chip itself or a bad input to the BIOS.

Given that machine was working fine, then sat stored for a year, now it won't work I think the most likely suspects are:
- Bad caps. (Not necessarily on the motherboard.)
- Static got to something.

What were the conditions where this was stored? Like: Cold, hot, humid, dry, did it get moved a lot?

"Stored" in my desk in normal conditions (stable temperature and humidity).
In your opinion, the need of a warming up to boot normally is a signal of bad caps? Visually i can't see anything wrong with them...

mp10 wrote:

If I turn on the computer (cold) and wait for 5/10 seconds and then turn it off, I can ear the hard drive spinning in the next try and then I need to wait for 1 minute to turn it on the computer again in order to boot completely.

This sounds almost like the hard drive is having trouble spinning up on the first try.
Really rare but I did once see a system that wouldn't start because a hard drive bearing had gone bad.

Obviously you are still connected to the hard drive.
For testing set it up this way:
Remove all add-in cards (except video if you don't have on-board).
Disconnect all the drives. (Both data and power)
Disconnect any peripherals. (Speakers, printers and such)
- This removes a lot of possible problems.
In this mode it should go though POST and then tell you something like "No Boot Device Found" or "No Operating System".
If it will consistently get that far then start adding the things you removed one at a time until the problem comes back.
.

mp10 wrote:

In your opinion, the need of a warming up to boot normally is a signal of bad caps?

It is a sign but it is not proof.
Aluminum Electrolytic capacitors work because of an oxide layer on the aluminum foil inside them.
When left sitting the oxide layer (some of it) will dissolve back into the liquid electrolyte. (It's not fast but it's worse with older caps.)
When you apply DC voltage an electrolysis type reaction starts happening which restores the oxide layer slowly.
(That is provided the layer did not get so thin that the capacitor shorts.)
When it's warm DC has been applied so the layer has built up a little bit but when it cools down that small build-up may dissolve right back into solution.

mp10 wrote:

Visually i can't see anything wrong with them...

I was an Electronics Technician by trade before I got into computers.
Capacitors fail without any visual signs rather frequently.
.

PCBONEZ wrote:

This sounds almost like the hard drive is having trouble spinning up on the first try. Really rare but I did once see a system t […]
Show full quote

mp10 wrote:

If I turn on the computer (cold) and wait for 5/10 seconds and then turn it off, I can ear the hard drive spinning in the next try and then I need to wait for 1 minute to turn it on the computer again in order to boot completely.

This sounds almost like the hard drive is having trouble spinning up on the first try.
Really rare but I did once see a system that wouldn't start because a hard drive bearing had gone bad.

Obviously you are still connected to the hard drive.
For testing set it up this way:
Remove all add-in cards (except video if you don't have on-board).
Disconnect all the drives. (Both data and power)
Disconnect any peripherals. (Speakers, printers and such)
- This removes a lot of possible problems.
In this mode it should go though POST and then tell you something like "No Boot Device Found" or "No Operating System".
If it will consistently get that far then start adding the things you removed one at a time until the problem comes back.
.

I tried that method and after waiting +/- 1 minute (without shutdown) the PC boot happens normally (probably with all the hardware attached the behavior is the same). Sometimes goes directly to the BIOS menu and other times boot normally.

mp10 wrote:

PCBONEZ wrote:

This sounds almost like the hard drive is having trouble spinning up on the first try. Really rare but I did once see a system t […]
Show full quote

mp10 wrote:

If I turn on the computer (cold) and wait for 5/10 seconds and then turn it off, I can ear the hard drive spinning in the next try and then I need to wait for 1 minute to turn it on the computer again in order to boot completely.

This sounds almost like the hard drive is having trouble spinning up on the first try.
Really rare but I did once see a system that wouldn't start because a hard drive bearing had gone bad.

Obviously you are still connected to the hard drive.
For testing set it up this way:
Remove all add-in cards (except video if you don't have on-board).
Disconnect all the drives. (Both data and power)
Disconnect any peripherals. (Speakers, printers and such)
- This removes a lot of possible problems.
In this mode it should go though POST and then tell you something like "No Boot Device Found" or "No Operating System".
If it will consistently get that far then start adding the things you removed one at a time until the problem comes back.
.

I tried that method and after waiting +/- 1 minute (without shutdown) the PC boot happens normally (probably with all the hardware attached the behavior is the same). Sometimes goes directly to the BIOS menu and other times boot normally.

You did what then waited 1 minute.

Turn on the PC and waiting 1/2 minutes.

Get it to boot then just leave it sit there running but doing nothing for about two hours.
The purpose is to build up the oxide layer in the caps.
After that try a hot-boot then let it cool off (say 1 hour) and try a cold-boot - then report back any changes.
.

mp10 wrote:

Turn on the PC and waiting 1/2 minutes.

I am confused. It sounds like you are turning it on twice.

PCBONEZ wrote:

Get it to boot then just leave it sit there running but doing nothing for about two hours. The purpose is to build up the oxide […]
Show full quote

Get it to boot then just leave it sit there running but doing nothing for about two hours.
The purpose is to build up the oxide layer in the caps.
After that try a hot-boot then let it cool off (say 1 hour) and try a cold-boot - then report back any changes.
.

Ok, i'm going to try. Thank you for your support.

PCBONEZ wrote:

mp10 wrote:

Turn on the PC and waiting 1/2 minutes.

I am confused. It sounds like you are turning it on twice.

My new "approach" is turn it on only once and wait 1/2 minutes.

Have you tried another PSU already? The more you talk about this issue the mroe I think you should eliminate that as a suspect. A problematic BIOS chip should just go haywire and lock up instead of consistenly booting after 30 seconds, but the PSU taking its seet time to assert the PWRGOOD signal (probably a good thing, if its doing its job) isn't that hard to imagine.

alexanrs wrote:

Have you tried another PSU already? The more you talk about this issue the mroe I think you should eliminate that as a suspect. A problematic BIOS chip should just go haywire and lock up instead of consistenly booting after 30 seconds, but the PSU taking its seet time to assert the PWRGOOD signal (probably a good thing, if its doing its job) isn't that hard to imagine.

Said tried a different PSU in the OP.
.
Slow to get to PWRGOOD is and indicator that the caps are charging too slow which indicates degraded caps but not necessary caps that are completely failed.
.
On a warm boot degraded caps may be able to hold the charge long enough for the next boot where as on a cold boot they have had time to discharge.
.
None of that explains why clearing the CMOS helps though.
Possibly there is more than one problem.
.

PCBONEZ wrote:

Said tried a different PSU in the OP. . Slow to get to PWRGOOD is and indicator that the caps are charging too slow which indica […]
Show full quote

alexanrs wrote:

Have you tried another PSU already? The more you talk about this issue the mroe I think you should eliminate that as a suspect. A problematic BIOS chip should just go haywire and lock up instead of consistenly booting after 30 seconds, but the PSU taking its seet time to assert the PWRGOOD signal (probably a good thing, if its doing its job) isn't that hard to imagine.

Said tried a different PSU in the OP.
.
Slow to get to PWRGOOD is and indicator that the caps are charging too slow which indicates degraded caps but not necessary caps that are completely failed.
.
On a warm boot degraded caps may be able to hold the charge long enough for the next boot where as on a cold boot they have had time to discharge.
.
None of that explains why clearing the CMOS helps though.
Possibly there is more than one problem.
.

Yes, I already tried with a brand new PSU.
The "clear CMOS" don't make any effect in this problem, it was a bad interpretation of my part, sorry.
Today I am going to test your solution. Can it be a long term solution or is something to find out the problem?

clueless1 wrote:

mp10 wrote:

I added this variable in my analysis and I found something: when the PC doesn't boot I leave it ON for a while (only fans running) and then I turn off. After that, the PC boot without any problem. Any hints about this behavior?

Yes, I'm using the front panel switches of my PC case.

To me that kind of sounds like cracked solder? When you leave it on for awhile, it heats up and expands and the bad solder connection becomes good, until it cools down again.

Similar issues are defective caps.
Cap gets loaded for some time and board boots after reset.

Does it boot if you give some pressure on the BGA Chipset ?