Diagnosing orientation disorder

The desktop (tower) PC has been suddenly 'dying' without notice, after varying numbers of minutes. The CPU heatsink fan stops turning, but a LED on the motherboard stays lit. I experimented with the RAM sims and slots, but got very inconsistent results. I tried to run MEMTEST to get a 'sophisticated' evaluation of the RAM, but the PC kept dying before the test ended. I thought I had heard some 'arcing' noise, so my next suspect was power supply. A replacement 'fixed the problem' ONLY while the PC was left on its side; when it was turned upright - as a tower is supposed to be - the problem returned. Any suggestions what loose connection to look for ?

 

Hi Sebastian. When a computer will only run on it's side there are a few possible reasons.
When on it side looks like gravity takes over and makes a proper connection.
Check the motherboard is not earthing out.
Remove ram sticks and clean connections, blow any dust out of seats.
Are the ram sticks securely clipped in?
Next may be a short in the CPU fan or the heatsink is not secured properly.
Check CPU fan to Mobo wiring and make sure clipped in firm.
New heatsink paste wouldn't hurt.
Download "Speccy" Free and check temps to see what the max the temp reaches.

http://www.piriform.com/speccy/download

 

The Heatsink matter rings some bells; recently I removed the heatsink fan to get access to the accumulated dirt in the heatsink; but in the process I damaged the lugs that hold the heatsink to the motherboard. Luckily, I found a very similar heatsink with lugs intact, and fitted that - using an entire new tube of paste. This 'dying' did not happen previously.

 

You never use a whole tube of heatsink paste.
Only an amount the size of a pea and smooth out evenly with something like a credit card.
Looks like something is still loose with the heatsink and only gravity is causing a connection when on side.
You need to clean all the excess paste off without scratching the surfaces and redo. Nail polish remover works.
Sounds like the heatsink is loose still and this will cause your problem.

 

Since your, and my post, I have had a look at the heatsinkfan, and indeed it was loose. Taking the other side off the PC does NOT expose the lugs of the securing studs for the heatsinkfan. So I have 'done my best, but blindfolded'. It seems to be more 'firm' now; as for the paste - good advice but too late. The failure has not yet happened even though the PC is now upright. If it is still working in an hour, Ill be satisfied that its fixed.

 

As stated never too late correctly by Dougie and Cindy. If any of that grease gets into the saddle, you lose the board and the cpu. If it gets into the pins same thing. That thin layer of cpu grease almost can't be slim enough but you all are scaring me with nail polish remover in the wrong hands too I'm afraid in case it might leave any film or get into saddle and short out system. Please isopropyl alcohol only.

 

Please use isopropyl alcohol, Sebastion.

I shouldn't have suggested using nail polish remover.

The main thing we have pinpointed your problem area.

 

Yup you guys were right on!!!! Nice call.

 

The tube was quite tiny - I would guess the contents would not have been more than pea-sized. Whereas the PC was cutting out after minutes before, it survived upright for an entire MEMtest (1 hour). As an aside, only half the RAM showed during that test; but by swapping the two RAM chips in their slots, the full complement of 2Gb now shows again. Oddly enough, the MEMtest was passed with flying colours, even though half the RAM was not reported during the test.

 

First of all memtest86 should really be run on 1 stick of ram at a time for best results and how many 8 pass complete tests did you run?

 

The MEMTEST I used was 4.3.6; I ran it (incompletely) several times, because the PC kept failing before the end. In at least ONE of those tests I saw that memtest recognised 2Gb; but the test that ran to completion (without error) it saw only one of the two RAM (1Gb) sticks. The number of tests ran beyond 14, but I can not recall what the final tally was. "8 pass complete tests" - I do not know enough about memtest to recognise that 'term'.

 

A complete test has 8 segments to it...