Power LED Flashing PC won't boot

[raysund]

Recently my PC whihc a Intel?AS motherboard with a Pentium 120 Mhz CPU started flashing its power LED and went into a continuous reboot. After some tinkering aroudn the computer completely quit doing anything at all. I know the inside of my PC since I assembled it. I checked everything, pulle and tugged on all cables and reinserted all boards in ther slots, blew off the dust, checke d the voltages on the power supply.
Only thing was the my + or - 12V leads were reading just slightly below at 11.9 v. I am not sure how tolerant the mboard is to all that. Any way I let it sit overnihgt and then booted it up next morning. Now it is fine.
However this is the second time it has happned to me. I feel somewhat insecure especialy wwhen I am logged on to PC banking and I am afraid I might loose my transactions and leave my account open.
Has anybody else faced this flashing LED problem with not beeps at all?
And what does a flshing LED mean? I could not find any reference to it any Intel or other PC repair website?

[Nathan]

It could be the power supply. But it sure sounds like it's overheating. Is it oveclocked? Are the cooling fans working OK? Including the fan on the CPU?

[raysund]

It does seem like overheating. But somehow I am not convinced. The CPU cooling fan seems okay. The power supply cooling fan is okay. It's a fairly new chassis. If it's a overheating CPU problem then it should take some time before this happens. What kind of system monitoring should I do to troubleshoot this? Any suggestions? I am runnning Win98.

[Axel]

First thing to do is truely identify the motherboard - get us any markings - especially an FCC number if it's stamped on the board, This might mean a complete dis-assembly as sometimes the FCC ID is on a sticker on the back of the board.

You might also be able to identify the board from the boot screen BIOS id - after the BIOS loads, but before the hard drives initialize, an ugly little alpha numeric string should appear at the bottom left of your screen - something like:

07/25/91 - vi440vx - 2P94556-00

Hit your <pause> key to stop the boot so you can write this down. <enter> will continue the boot.

That can identify your BIOS, motherboard, and IO chip set for you. I'm not near my notes or tech links, but will be next Mon - then I can reference the site that will tell you what the string means.

You might have a failing EPROM chip which contains your BIOS information. The reason I say this is, if the BIOS were working properly and you have another bad system component, you'd probably get BEEPS indicating both the maker of your BIOS and the system failure.

Also, track down the LED source - is it to the mobo (fan, power, reset, etc. etc.) or does it go directly to the power supply or the hard drive?

Let's start there, then you'll get more of a response from us.

[raysund]

My Motherboard is a Intel/AS motherboard(is that what y'all call mobo?) with a 120 MHz processor, no overclocking etc.
The Power LED is connected to the front panel connectors provided on the front edge of the mobo. At present I am back to blinking LED and I cannot do anything from my home PC. But just very briefly this morning it booted up and went through up to the Windows98 logo before going back to blinking pwr LED again. Then the video goes out and the monitor LED turns from green to amber indicating that it has lost video signal from the PC. I have another pwr supply on an older chassis. But that is rated only 200W compared to 250W on the present one.
I have the following devices installed:
1) hard disk Quantum 4.3g
2) hard disk conner 450 mb
3) Internal ZIP disk
4) A CD Rom Sony CDU 311
5) A 1.44 mb Floppy drive
I disconnected the video pwr cord from the back of the chassis and plugged it directly to an external pwr socket on the wall to prevent draining power from the chassis' pwr supply.
Have I missed any other vital info?

[800XL]

The Intel Advanced/AS (aka Atlantis) is an older board, 430FX chipset if I recall. Drop that other power supply into the mix right off. 200W should be enough to power most of what you have running there at least for testing purposes. It really sounds like the power supply is going and you need to start eliminating some of those potential causes of the problem.

The other thing to look for would be components on the motherboard getting very hot. Check for parts that are heating up in the amount of time it takes before the thing shuts itself down. Anything that is getting very hot could be a sign of a part that is going/gone and the cause of your problems.

[raysund]

All helpers,
Thanks very much for the advice. 800XL you were right. I did look through all the websites including support.intel.com and foudn the flashing LED, PC wont boot symptom discussed there. I systematically removed and replaced everything and finally took it to the place I bought the chassis and replaced the power supply.
I am sending this reply from my Home PC. It seems to be doing okay now.

Thanks for the helptoall who responded.

This topic can be closed now unless someone else now need my knowledge base on this subject.