CPU fan spins, but no post, no beeps, no LEDs. Do I have a dead motherboard, CPU or both?

[Richy1985]

Hi everyone,

I have an old Pentium 'Advanced AS Motherboard' that was working fine up until a few months ago. I have a passion for old motherboards of the Pentium/486 era and I want to be absolutely sure that the motherboard is dead before I say farewell and give it the heave-ho.

So, what are the symptoms?

When I push the Power button the CPU fan spins and that's all. There's no beep codes, no post, no display and the LEDs do not power on. If I remove all the RAM and power on, there are still no beep codes.

The good news is that I have ruled out the 230W Power Supply, RAM, Hard Disk and Graphics Card - all these components work fine. The board also comes fitted with L2 Cache Memory and this has to be pushed very tightly into it's socket in order to obtain a display. I don't think this is the issue though, because when I encountered this problem in the past the LEDs would still light up.

Am I looking at a dead motherboard, CPU or both?

 

[kenghtt]

I'd have to say dead motherboard. There should be beeps when you remove rams if your motherboard was still good.

 

[ngrego]

If it was working fine till a while ago and now it wont start you may need to prepare yourself for the worst. Before tossing it out I would bench it one last time. Strip it down, dust it off an reassemble part by part starting up after each is installed. If that doesn't do it then its game over unfortunately.

On the other hand if it doesn't take up too much space, stash it away for a while in case you find more spares in the future.

 

[Chicano]

A) You have to make absolutely sure the PSU is OK because they sometimes appear to be ok but are not... the only way to know for sure is with a PSU tester or trying another PSU that's known to be good.

B) You can also try resetting the BIOS. I have had this problem and resetting the BIOS helped.
1. Remove the computer power cord,
2. Remove the BIOS battery
3. Push the power switch and hold it in for a full minute before releasing it.
4. Check the PSU connectors to the motherboard
5. Wait 5 to 10 minutes before putting the battery back on
6. Connect the power cord to the computer
7. Switch the computer on

If the monitor remains blank after trying another PSU and resetting the BIOS, the motherboard is probably dead. Check if it has bulged, blown, or leaking capacitors.. if it has, replacing them may help... I've had a few Intel mobos that suffered the same issue; A socket 370 and two socket 478. The 370 just got tired, no caps appeared to be damaged, but it just started taking to long to start posting and later nothing... a D845GLAD had only one slightly bulged CPU capacitor but I don't think it was the cause because I've known of others that had worse caps and still worked... And a D845GLLY did not post anymore one day after a period of Windows instability, and no capacitor damage was apparent. Seems that Intel mobos just croak without much warning when their time is due.

 

[Richy1985]

Thank you all for your replies.

I believe the PSU to be fine because I installed another motherboard of a similar age into my computer and it works fine. This other, old motherboard will not support the CPU in the potentially faulty board so I can't test the CPU to rule that out.

I will now try your BIOS battery suggestion. It takes a 2032 coin cell battery.

All the motherboard capacitors appear to be healthy.

 

[Richy1985]

I have tried the BIOS battery suggestion and still nothing. Should I get another CPU off ebay just to be sure?

 

[Chicano]

If you don't mind the ($15-$20*) expense of another P4 or Celeron CPU, that will probably determine the problem. But CPUs almost never are the cause afaik. From all the posts, articles I've read, and personal experiences, a bad CPU is rare, not one bad CPU in my dead motherboard cases, 3 Intels and 1 Biostar.

Only if you have reason to believe the CPU overheated, you can suspect of it, as heat is about the only thing that permanently damages them.. but if it did not overheat, another CPU will probably not make a difference.

You could remove the CPU and check it for heat marks on the heat disipation shield.. that's where the CPU info is (the metal plate that makes contact with the heatsink).. and check also on the motherboard around the CPU socket. If you don't see any heatmarks present, the CPU is probably good, but check the web articles for detailed symptoms of a damaged CPU.

How Can I Tell if My CPU Is Bad?
http://smallbusiness.chron.com/can-tell-cpu-bad-65437.html

*I've seen some lower displacement Pentium 4s for as low as $9 on eBay.

 

[Richy1985]

I will purchase another CPU off ebay. I can get one with the same model number for under £4, so it won't be a disaster if it is indeed the motherboard.

 

[Richy1985]

It's pretty much confirmed now - the motherboard is dead.

 

[Kyle Leggat]

did you try replacing the power supply

 

[Kyle Leggat]

maybe the motherboard isnt getting enough power from the PSU

 

[Kyle Leggat]

by looking at the previous posts i think the motherboard is bad

 

[volcob]

if there is no beep no screen up. but the fan is spinning and adjusting its speed plus the CPU is heating up. are those possible if not affirmative indication that the mobo is working? mine went up that way.

 

[silasdemone]

i know this is very old, but it was a dead mobo right? im having a similar problem now, fans spin, no post, nothing on my monitor, no beeps, no lights, ive tried different gpus, different psu.

 

[Richy1985]

i know this is very old, but it was a dead mobo right? im having a similar problem now, fans spin, no post, nothing on my monitor, no beeps, no lights, ive tried different gpus, different psu.

I believe my motherboard was dead. I sold it. I never put motherboards in the trash as I feel there might be someone else out there with more experience than I, who might be able to get it running again.

Good luck trying to get yours to work.

 

[silasdemone]

awesome, your cpu was fine though?

 

[Richy1985]

awesome, your cpu was fine though?

I suspect that the CPU was fine.

In my experience of working with motherboards, it's rare to come across a damaged CPU. I've been working with computers since 1993, when I was a child. In that time, I think I've only encountered a damaged CPU one time, if that.

If your CPU does not have a charred appearance, and it does not smell like it's burning, then I suspect it is O.K.

Sorry I can't give you a more definitive answer.

 

[Richy1985]

awesome, your cpu was fine though?

You've probably thought of this, but do you have another motherboard that is the exact same specification as your dead motherboard?

My old Pentium motherboard is configured to run a 100 MHz CPU. Whenever I encounter a problem with the motherboard, I take the CPU out and install it into another Pentium motherboard that is also configured to run a 100 MHz CPU. If the other motherboard boots up, then I conclude that there is no problem with the CPU.

Hope this helps.

 

[Chicano]

i know this is very old, but it was a dead mobo right? im having a similar problem now, fans spin, no post, nothing on my monitor, no beeps, no lights, ive tried different gpus, different psu.

You've probably thought of this, but do you have another motherboard that is the exact same specification as your dead motherboard?

My old Pentium motherboard is configured to run a 100 MHz CPU. Whenever I encounter a problem with the motherboard, I take the CPU out and install it into another Pentium motherboard that is also configured to run a 100 MHz CPU. If the other motherboard boots up, then I conclude that there is no problem with the CPU.

Hope this helps.

CPUs are rarely the cause and I also have never seen one dying, and I consider dead CPUs a thing of the past when they could burn up but it's been a long time since that and they all are now designed to throttle down and shut off before suffering heat damage.. the only thing they can be vulnerable to is electrical damage.. I'm not sure about Electrostatic Discharge but that can't happen when the CPU is in the socket so that's the very last component to suspect of failure.

The last tests you can do to an apparent "dead" motherboard are 1) Reset the BIOS and next 2) Restore the BIOS... a corrupted BIOS can resemble a dead PSU, dead motherboard, RAM issue, dead CPU, etc. So after having ruled out all except the motherboard, before declaring it dead, do a BIOS reset to clear out corrupted settings, and if necessary, follow with a BIOS Recovery. I use the methods specified below and they work except when the motherboard is dead... but if you can find a specific Recovery method for the specific motherboard make and model that should be followed instead.

Start with a BIOS reset and if necessary follow with a BIOS Recovery.
Option A) Bios reset:
1. Remove AC power or turn off the PSU
2. Remove the battery
3. Move the BIOS jumper to pins 2 & 3
4. Press and hold the power button for 60 seconds
5. Wait 10 minutes
6. Revert 1 through 3 and try the computer

Option B) Bios recovery:
1. Remove AC power or turn off the PSU
2. Remove the battery
3. Remove the BIOS jumper
4. Press and hold the power button for 60 seconds
5. Wait 10 minutes
6. Revert 1 through 3 and try the computer