What causes a computer to fail to post?

[Titanion]

I just built a computer from old parts for my sister, and in doing so, I pulled a 64MB stick out of a 1999 vintage SS7 Matsonic motherboard. When I put my computer back together, after removing the ram, it now will not post. It was running great, and I used it as my 3rd computer on my LAN.

How many different reasons can cause a computer to not post? I get no image; I cannot get into bios. I have played around with it for a few days, trying various things, and still, it will not post.



<font color=red><b>To reign is worth ambition though in Hell:
Better to reign in Hell, than serve in Heav'n.</b></font color=red>
John Milton, <i>Paradise Lost</i>, II 262-263

 

[Coyote]

I did something similar a while back. I had to clear the CMOS to get it to boot. Upon booting go into BIOS and set that back to original state (my ram timings had been changed preventing boot with the other ram) Perhaps you will have some luck trying that.

EDIT: Are you getting an error code from the mobo, either LED or beeps?

XP 2000+
MSI KT3 ULTRA-2 KT333
Maxtor 60GB ATA 133 7200RPM
512MB PC2700
ABIT G4 Ti4200 OTES 64MB
Win98SE<P ID="edit"><FONT SIZE=-1><EM>Edited by Coyote on 11/25/03 01:46 PM.</EM></FONT></P>

 

[Titanion]

The first time i attempted to boot up after removing the ram, I did stick another 64MB stick in it. I was not sure what is was. It may well be some old EDO ram or something, but I was not sure... could that mess things up? I have cleared cmos, and I have taken out the battery for 10 seconds or so. I have changed PSUs, and I have tried an old pci video card instead of the Voodoo 3 I have in the AGP slot. I have tried all kinds of things.

I have not taken everything out and rebuilt it from scratch... but if it is a ram confusion thing, rebuilding would not help, would it?

<font color=red><b>To reign is worth ambition though in Hell:
Better to reign in Hell, than serve in Heav'n.</b></font color=red>
John Milton, <i>Paradise Lost</i>, II 262-263

 

[Coyote]

Sometimes I've tried leaving the battery out for a couple a minutes, no luck. For some reason it took overnight (clearing jumper and battery out) so try that. <b>Also, are you getting any beep codes at all? Does it have LEDs? if so look at those and it will tell you where it's hanging on POST.</b>

EDIT: Post the system spec.s (we can only see what mobo the old ram came out of). It sounds like everything was working until you put that old stick of ram in. So my assumption is that caused the problem. Or did you also do other things -move the mobo/cpu/ram to another case etc?

I'm worried I may be making too many assumptions. For example you say "When I put my computer back together, after removing the ram,..." Upon closer reading you don't actually say you tried to boot w/old ram. I'm assuming you assembled this baby from working parts, added the old ram and then tried to boot (for the first time). Then removed it and so on. Please elborate a bit on the steps etc. At this point for all I know it could be you unassembled the working 'puter, put it together in another case and accidently grounded the mobo. In which case it prolly w/n try to post and hence ram settings w/n have even been affected by old ram? Do elaborate to help us not go off in wrong direction

XP 2000+
MSI KT3 ULTRA-2 KT333
Maxtor 60GB ATA 133 7200RPM
512MB PC2700
ABIT G4 Ti4200 OTES 64MB
Win98SE<P ID="edit"><FONT SIZE=-1><EM>Edited by Coyote on 11/25/03 05:42 PM.</EM></FONT></P>

 

[Titanion]

I have been posting from work, so I will find specs when I get home. No, all I did was take ram out.

Suppose this motherboard is sensitave to ram, can one stick it reads well get it up and going, posting, and once up, it reads all the ram in it. I am tempted to get that pc 133 64MB stick back to see if it posts.

I will try leaving the battery out overnight.

I will get that ram back on Thanksgiving, and give her a 32 MB stick instead... 96 instead of 128 will do her fine... and I want my computer back... not that I ever use it, but just in case I get enough people over to have a 5 computer LAN game of Baldur's Gate or some other old game a 550 MHz computer can play.

<font color=red><b>To reign is worth ambition though in Hell:
Better to reign in Hell, than serve in Heav'n.</b></font color=red>
John Milton, <i>Paradise Lost</i>, II 262-263

 

[Coyote]

So all that happed is you took out one stick of ram? And now it won't POST. Yeah, get that stick back and give it a go.

BTW, you had me confused when you said "and when I put my computer back together" etc.

XP 2000+
MSI KT3 ULTRA-2 KT333
Maxtor 60GB ATA 133 7200RPM
512MB PC2700
ABIT G4 Ti4200 OTES 64MB
Win98SE

 

[sjonnie]

If the MOBO will not come into the BIOS is could be for a number of reasons

1. No power to main board
2. Main board failure
3. CPU failure
4. RAM failure
5. Video card failure
6. BIOS error

In all cases (except 1.) you should be getting <A HREF="http://www.villagegeek.com/downloads/amibeep.pdf" target="_new">BEEP CODESs</A> from your computer speaker. These diagnostic BEEPs will help you to find out what the problem is. If you are not getting BEEPs check for the power LED on your main board or if that is not working check your power supply by plugging it in and shorting pins 14+15 on the ATX connector.


<A HREF="http://www.anandtech.com/myanandtech.html?member=114979" target="_new">My PCs</A>

 

[jimbo99]

You could also be shorting. Take the mobo out and put it on a phonebook plug in only the minimum.

There are other issues as well.

Taking the battery out for 30 seconds or even a few minutes is often not enough time for some older boards. On my a7v333 board I noted that it took nearly 20 minutes to clear when I did it the other day.

Clearing the cmos jumper works properly when you unplug the power supply and discharge the mobo. Unplug and hit the power button to discharge. If you have the option of clearing cmos with a jumper you should choose that option over pulling the battery.

If you want to hear the beep codes you have to make sure you have a speaker attached or have a buzzer built into the mobo. Also, not all failres will always result in beep codes.

One thing to keep in mind is that if you didn't have problems prior to your swapping, and nothing of note happened to any of the components during the swap, then most likely all your components still work.

 

[Coyote]

Had another thought. If your computer is pretty old and you originally had 2x64mb of ram. Then removed one of your 64mb sticks to give to her and replaced it with the 32mb stick you mention. You would have 1 stick of 64mb and one of 32mb - I think I remember that some of those older systems would'nt work. If you had 2 sticks of ram they HAD to be the same.

Does anybody remeber that? What was that called?

XP 2000+
MSI KT3 ULTRA-2 KT333
Maxtor 60GB ATA 133 7200RPM
512MB PC2700
ABIT G4 Ti4200 OTES 64MB
Win98SE

 

[pIII_Man]

or you could just remove the battery and flip it over, wait 5 seconds and repace the battery the way it was. Voilla, Cmos cleared in 10 seconds


If it isn't a P6 then it isn't a procesor
110% BX fanboy

 

[jimbo99]

/smile

 

[Titanion]

Thanks for all of the input guys... I did get the ram back, but I have not tried it out yet. If it works, great... if not, I will be tempted to take the entire system apart and put it back together from scratch.

What I had was 2 64MB sticks and 1 128MB stick. I took one 64MB stick out. Then I added a different 64MB stick--that might have been edo ram, still not sure, but it is currently stable in a different computer with a 66MHz bus. The computer would not boot. I took out the unknown 64MB stick of ram, but then the computer still would not boot. I changed the order of ram. I added a different pc 100 stick of ram and took the other two out. I removed all pci cards. I removed agp card and booted with pci video card. I reseated agp card. I tried a different psu. I got frustraited...

I have removed the battery overnight, with the jumper shorted and the computer unplugged.

It is a lot of work for a crappy old computer... I must love the challenge...

<font color=red><b>To reign is worth ambition though in Hell:
Better to reign in Hell, than serve in Heav'n.</b></font color=red>
John Milton, <i>Paradise Lost</i>, II 262-263