PC wont boot, cuts out 2

[birney29]

Hi,

im looking for some advice. i have a pc that when it is turned on, it will power up for about a second (fans turn) then cut out dead. if i turn the switch off at the wall, and leave it for a min, then try to boot again, it will do the same thing. ive already switched power supplys with a working pc, but the same thing is happening, so it cant be the power supply. any ideas?

Kenneth Birney
User Interface Programmer
Scottish Police

 

[franklin97355]

Make sure the cpu is seated correctly and the heatsink is on tight.

 

[birney29]

When i got the computer last night, the fan/heatsink was lying disconnected. i ra-attached it, loosely over the cpu. do you think that could be the problem?

Kenneth Birney
User Interface Programmer
Scottish Police

 

[BadBigBen]

Hi there, what iaanbe and franklin97355 have said is correct and should be checked up on...

I've found that when you receive (build) a new system, starting off with clearing the CMOS (BIOS settings) usually takes care of alot of probs like no booting...

check also if your HS (heatsink) fan is plugged into the right connector and that it is the correct one for the CPU in use, could be that the mobo's circuitry isn't detecting the fan and shuts the system off (to prevent heat damage)...

Ben

 

[birney29]

excellent, ill give that a try. to clear the CMOS, i remove the battery? ive never did that before, but ill give it a whirl. what could possibly go wrong!

Kenneth Birney
User Interface Programmer
Scottish Police

 

[fenix]

2 cents.....also, bios's vary and your motherboard may have a set of pins to jump instead of having to remove the battery. If you didn't lose your time, then you haven't reset. Sometimes the battery must remain out for 10 minutes if there are strong capacitors in the system.

Some bios's make you go into your maintenance menu (when you need to reset the clock). Usually this type has a jumper than gets moved over one set of pins to get in, than is returned to go into normal run mode after the time is set.

 

[paparazi]

birney29 QUOTE!!
"When i got the computer last night, the fan/heatsink was lying disconnected"
What do you mean???
It is absolutely critical that the heatsink is fitted the correct way and clamped down onto the CPU!! please explain what has happened, have you tried to turn on the PC with this heatsink/fan detached?
Please more info and PC specs.
Martin

Replying helps further our knowledge, without comment leaves us wondering.

 

[birney29]

When i recived the computer, the heat sink and fan was literally lying outside the case. The peole who own it, have tried to turn it on without it being attahced. why? i dont know. I reatached the fan before attempting to turn it on.

Kenneth Birney
User Interface Programmer
Scottish Police

 

[Freestone]

"i ra-attached it, loosely over the cpu"

As Martin posted earlier, the heatsink must be clamped down over the CPU. What do you mean by reattached loosely? Also, at this point, the heat sink may require a cleaning and reapplication of heatsink grease or a thermal pad to, but not both.

On newer systems, the CPU fan is attached with a three wire cable to a motherboard connector specifically labelled for the CPU fan. BIOS will examine the rotational speed of the fan via this connector, and if the detected speed is out of range, BIOS will shut off power in hopes of preventing an overheated CPU. If the CPU fan cable has three wires, confirm that it's plugged into the correct connector.

Another possibility is a short somewhere in the system. Power supplies usually have over-currrent protection built into them that shut down the unit upon detection of an overload.

 

[paparazi]

birney29
It depends on what processor/system it is as to wether the CPU is now damaged.
With most socket "A" systems (Duron/Athlon) the CPU is definately fried but with older Pentium 1's and AMD K6, Cirix which were much cooler CPU's you may have gotten away with it!!
P4's have thermal throttling, so if they get hot they power down.
Martin

Replying helps further our knowledge, without comment leaves us wondering.

 

[jurgen36]

Well if the CPU fan was not connected or even fitted (lying outside the case) then I would suggest that the CPU is cooked. If it is an Intel it might still be ok as it shuts down during overheating. If it is an AMD it will be scrap within 3 to 5 seconds. Try to loan, beg, borrow or steal another CPU, fit it and make shure that the fan is connected and seated the proper way. Then try again. Good luck

Jurgen

 

[birney29]

Fixed!

As embarresed as i am to admit this, i had the fan sitting the wrong way round. buggger. ah well. as soon as i got the fan clamped on, hey presto, bob's yer uncle, its alive!!

thanks for the help boys/girls

Kenneth Birney
User Interface Programmer
Scottish Police

 

[BadBigBen]

Birney29,

glad to hear that it's fixed and working... and give franklin97355 a star for suggesting the correct procedure (it would be only fair)!...

Ben

 

[birney29]

already have! cheers boys

Kenneth Birney
User Interface Programmer
Scottish Police

 

[paparazi]

birney29
I hope that there was a thermal pad fitted or clean paste applied before you refitted the fan??
This is very important for the heat to transfer from the CPU core to the heatsink base properly.
Glad to see you fixed it, alarm bells were ringing when you said the heatsink/fan was detached.
Martin


Replying helps further our knowledge, without comment leaves us wondering.