Tech Support Guy banner
Status
Not open for further replies.

PC won't boot, fans at full speed

12K views 8 replies 2 participants last post by  lightenrod 
#1 ·
I have a Dell Optiplex GX 280 medium tower with XP Pro. It was working great and I sent it to my son via UPS. When it arrived. It wouldn't boot at all. I now have it back here.

When you push the power button, I get a yellow light and the fans turn on but run at a very high speed. On the inside I get a constant yellow light which indicates a hardware failure.

I have disconnected and reconnected everything several times, changed the memory, cleaned the processor and added Arctic Silver 5 to the CPU and Northbridge.

The CD-ROM tray works but won't read anything. It won't start in safe mode and won't bring up "set-up" or "boot sequence". The screen never shows anything.

I found a couple of problems similar to this on Google but have tried everything that anyone suggested.

My question: Is there anyway to isolate the problem. It's an older computer and not worth the expense of just replacing parts at random.

Any suggestions appreciated.:confused:
 
See less See more
#2 ·

Attachments

#6 ·
You stated in post #1; "cleaned the processor and added Arctic Silver 5 to the CPU and Northbridge."

Exactly what did you do to the northbridge? There would be either one or two silver wires that run across the northbridge and connect to "eyelets" of "loops" on the motherboard. How did you disconnect the wires that run across the northbridge? How did you reconnect the wires to the "eyelets" or "loops" on the motherboard?
 
#7 ·
I just depressed one end of the spring wire that crosses the northbridge, slid it back just enough to clear the loop, then lifted it straight up. There was only one spring wire.

I cleaned it up with pure grain alcohol, added a tad of Arctic Silver 5 and reinstalled it the same way by hooking one end of the spring wire, seating the northbridge and sliding the spring wire back into the loop. The northbridge had to move slightly while hooking the spring but I couldn't any other way of doing it.

The problem was already there before I ever messed with the northbridge. In fact, I didn't even know what a northbridge was until I was looking at the MB schematic during my troubleshooting.

Did I make matters worse (if that's possible)?
 
#8 ·
The wire than runs across the northbridge heatsink and connects to the "eyelets" or "loops" on the motherboard is part of the overheat circuitry. In some cases on Dell machines I've seen on of the "eyelets" or "loops" break the solder connection on the board and come loose. When this happens, the machine will not boot since the oveheat circuitry believes the machine is running hot since the circuit has been broken.

On Dell machines with BTX form factor motherboards when the fan "roars" and there is no display it is generally indicitive of a failed motherboard. Since your machine has an ATX board I don't believe this would necessarily apply.

There is also a known problem with Optiplex machines fan running fast and loud that is caused by a audio driver conflict. In this scenario the fan just runs fast and loud, but you still have a display.

The fact that on your machine the fan runs fast with no display leads me to believe that for some reason (?) the machine believes that it is overheating and not booting. What I would do to begin with is pull the board out, turn it over and with a magnifying glass carefully check the solder connections on the "eyelets" or "loops" on the back of the board. You might first remove the wire that goes across the northbridge heatsink from the "eyelets" or "loops" and try to "wiggle" them gently to see if one feels loose.

Since the machine worked prior to shipping, it is very possible that some portion of the overheat circuit was damaged in transit.
 
#9 ·
Win2kpro, thank you very much for your help. I checked the northbridge heatsink eyelets and they are secure. I feel sure you are right about it being the MB.

I'll just put it out to pasture and use some of the parts.

Again, thank you very much for helping me make an informed decision.
 
Status
Not open for further replies.
You have insufficient privileges to reply here.
Top