How to diagnose a computer that will not start?

When I turn my computer on the lights on the front immediately come on, but flash off every second or so. There is also a mechanical sound that is in time with the lights flashing. It continues this for 3 minutes or so, then all lights go off. Then one DVD drive light blinks on, and about a second later the second DVD light blinks on. After that the whole process repeats. Nothing ever shows up on the screen, which I'm thinking would indicate it is failing before the bios really starts.

Once or twice this week the computer shut down all by itself. Today it did this twice, again when I was not around. Now, it won't start, past what I described above.

Where do I start? One search suggested it may be bad memory? It is behaving like it was when new and there was a bios conflict with the memory slots I used. I don't suspect overheating as it was cleaned not long ago.

The MB is a Gigabyte EP45-UD3R S775 with an E4300 Intel processor. It is significantly overclocked. It has two sticks of 1 GB each, Kingston 800MHz DDR2.

All suggestions appreciated. I'm going to give it a go tomorrow.

 

There is a difference btwn clean and poor contact of the CPU HS. Intel make those horrible "plastic lugs" that hold down the HS onto the CPU. They "POP" and allow the CPU to heat up very quickly and can kill them.

-Lay the PC on it's side and remove the panel,
-You need to give the CPU HS a firm "wiggle" and ensure no movement,
-Remove and reseat RAM. GPU etc,
-Try testing RAM modules individually,
-Listen to BIOS beep codes.

 

A bit of an update. When the computer is failing to post, there is a set of 6 led lights on the MB. The first green one stays on solid. The remaining 5 flash at the same frequency as the system lights. Not sure but I think the noise I hear is the floppy drive starting and stopping. I put my hand on the floppy drive and the thing booted up normally. It only ran for a couple of minutes and then shut down by itself. So still checking.

 

It turned out to be a bad power supply.

 

Thanks for posting back!

I had looked at several threads relating to the POST LEDs and couldn't find any solutions. It seems that your problems with that board are quite common. Several people had tried different PSU and memory but no change. I'm glad the new PSU worked for you.

 

Yes, it was a costly experience, as I was so convinced it was the motherboard, that I bought a new one. At least it was on sale... New board performed identical, so it really only left the PSU as the possible problem. Hopefully some others can benefit from my experience, and get to the source of the issue much faster/cheaper than I did.

I had case power, case fan power, LEDs lit on the board, and CPU fan power, so I really did not suspect the power supply. I don't believe it is the design of the power supply as it has worked well for months. One section must have failed. Also I am now running it with an identical power supply from another computer - Antec 450 Watt SmartPower. Will have to find another replacement tomorrow.

It sure would be nice if the power supply manufacturers provided you with a test block with the voltages marked on them. Then you could just check them all in a few seconds and know immediately what is wrong.

 

I was going to say to kill the OC first. The issue of having a bad Antec would have also led me to believe something else was wrong since you had a 'significant OC'. Antec is a great brand but crap happens.

 

Maybe just kill the floppy from the boot-up list?

 

You can use a DMM to manually test a PSU, or spend a few $'s and get one of these: http://www.tigerdirect.com/applications/SearchTools/item-details.asp?EdpNo=1647108&CatId=1107

Glad you got it fixed. I go crazy with my PSU's now, no more cheap ones for me. Might be a good idea to test the voltages on your replacement PSU, make sure they are good.

 

"You can use a DMM to manually test a PSU"
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I have a DMM. How do you go about doing this? On some cables there are extra plugs, so no problem. The serial ATA plugs are very small. How do you test them? On the main power and 24 pin, do you just pull the plug from the board and measure the open end?

 

You put the end that would usually go in the HDD in the tester.

Burrell

 

I just test the regular molex plug, with the PC on. I searched MajorGeeks, and did not see a guide, hope I did not miss one. This seems like a decent guide. http://www.devhardware.com/forums/p...a-multimeter-how-to-use-it-to-test-75111.html

But be careful. If you have any questions, post them before trying it.

 

Went with an Antec TruePower New TP-550 replacement. Will probably do some careful voltage testing once it is installed.