Diagnosing problems with heat fried machine

[Simaril]

My son's desktop committed suppuku last week, apparently due to ongoing heat damage. Turns out that having dogs can be dangerous to more than just cats -- there was an accumulation of dust and dog hair on the intake fan filter that significantly retarded air flow.

When things began acting wifty, he started up some diagnostic software that included thermal sensing alarms...and found that everything was in the red. The motherboard was running above 55C, and another sensor was flickering randomly from 35 to 60C (implying it was damaged itself, I think). Not long afterwards, the machine wouldn't recognize any devices (including the hard drives). Boot attempts stalled at an infinte "detecting drives" screen. We assumed the motherboard was fried and acted from there.

We ordered a new Mobo, but when it arrived we realized we didn't have any thermal paste to reinstall the CPU. So, another order to newegg..and another 1/2 week waiting. Parts all arrived today, but unfortunately the problems aren't over.

We installed the mobo without problem, and cleaned the heat exchange surfaces of both the Core2 Duo CPU and cooling fans. Since the manufacturer's paraffin transfer material was present, we cleaned that off with 99% rubbing alcohol per directions (from arctic silver website). While the CPU dropped in without difficulty, we strugged some with the locking pins on the CPU cooling fan assembly. That went down eventually without any undesired cracking sounds...

Vid card inserted without problems, and the annoying little connectors for chassis usb and front sound jacks eventually got where they needed to go. Dan finished the setup and external cable connections....but then we found that they chassis to mobo connector plate needed to go in first, so we had to undo the mountng screws and start over installing the motherboard! No problems except gnashing of teeth...

But, after external cables connected, we now have nothing coming up at all. The power LEDs come on for the mobo and for the vid card, so juice is flowing. The fans are running fine. However, we get nothing out of the system at all. The monitor shows only the "analog signal" for a few seconds then goes black -- we're getting no indication of BIOS at all.

Now I'm not sure what's going on at all. Did we make a bad diagnosis in the first place? Did we screw up the reinstall? Or, did something really catastrophic happen? (He just told me that as he was connecting the vid cable to the vid card, wtih the case closed up and power off, there was a static spark <cold shiver down spine>)

Would appreciate any tips -- especially regarding best way to approach diagnosing the problems so we make the right next steps. I don't want to slowly rebuild the computer by guessing what could be wrong one step at a time!



(PS - this was a reminder to me of how important it is to keep up with maintenence. After his initial problem I cracked my case, cleaned all fans and filters --> and found the internal temps drop by 12 degrees centigrade!)

[Fulmar]

Well if you're 100% sure the motherboard you ordered wasn't DOA.  The signs I believe initially would point to the video card if you're not getting any Video output.  Is there an internal speaker with this system?  Does it beep when booting up (multiple beeps usually mean an error).  It can be helpful sometimes to have an internal speaker if you don't.  Some motherboards with onboard sound chips (like my 5 year old Asus board) would have an audible warning spoken through your desktop speakers during boots if there was a problem.

You'll need to try and and go through each part.  If you have more than one chip of RAM, try just one chip, and then try the other.  Try booting with a different video card if possible.  Don't hook up any Optical drives (I one had a bad CD-ROM drive prevent a system from posting).  Try a different PSU.  I know you said you cleaned out the case, but did you clean out the PSU as well?  Heat can damage those as well.  Perhaps the PSU isn't putting some electricity across all the power rails (12V, 5V etc).

You'll need to break it down and try one part at a time and make sure it works.  It's helpful to have a similar computer (that uses the same parts) as you can test each part in a known functioning computer.

Also, whatever model information you have give us is helpful as well.  If it's an Compaq, Dell, whatever.  Or is it homebuilt, what parts are inside it etc.

[Simaril]

It's a homebuilt. Here are the specs (before the fry -- now same except new mobo is Asus P5Q)

Motherboard.............P5W DH Deluxe
CPU.......................... Core 2 Duo 2.4
RAM.......................... 2GB of PC6400 DDR2-800 Crucial RAM
Hard Drive................Western Digital SE16 250GB SATA
Video Card...............HIS Radeon X1900XT 512MB
Drives....................... HP 16X CD-ROM DVD Burner With LightScribe, IDE...link to hard drive
Sound Card..............None for now
Operating System....MS Windows XP – Pro       
Power Supply...........Antec TruePower 2.0 TP2-550W

[TilDeath]

AS Fulmar said connect a speaker so you can get the beep code error.

I would start by removing all devices including the Video card and mem and see if it will give error there.  Then install mem (if using more then one stick install only one then switch) and listen to beep code. If all good so far move to installing the Video card.  In addition make sure the proper connections from the PSU to the MB are made with the proper connectors (ie not using the 4 pin PCIe native if it has one).  Install all devices one at a time to find the bad component.  As he said could be DOA board too.

[Reschke]

First things first....get rid of the dogs in the same area as the computer or just get rid of the dogs...I am currently pushing for the second option with my computer room since I think dogs should live outside all the time.

[Kermit de frog]

Take your CPU out and re-insert it properly.
The CPU should seat extremely flush.  Make sure it's in the UNLOCK position before inserting the CPU.

[Simaril]

Was pretty careful with the CPU seating in the first place, so don't really think that's it.

And Reske -- we're enough dog lovers that outside's just not gunna happen. We're concentrating on keeping the vents clean....

Will be trying the step by step component approach. How would one tell if the new mobo was the problem -- short of putting the old one back in with the processor reseated?