# Touching the chassie makes the computer freeze



## Langos (May 4, 2006)

Hi!

Since I upgraded and changed chassie, psu and motherboard to Antec P180B, Cooltek 500W psu and a Asrock DUAL VSTA 939 my computer has been freezing seemingly randomly. But then I decided to make a more thorough investigation into the cause of the freezings. I've come to the conclusion that my computer will freeze instantly when the inside of the chassie or the cpu-heatsink comes in contant with the "outer"-part of the chassie or anything else metal like a screwdriver etc.

It's a really odd thing because the computer is completely stable as long as nothing made from metal touches the inside of the chassie. I dont get a zap when I use a knife or screwdriver to touch for instance the heatsink on the cpu and if I grab the chassie with my bare hands nothing happens at all. 

:4-dontkno 

Any suggestions what might be wrong?


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## carsey (Aug 19, 2006)

Looks like something is shorting-out somewhere on the case. Did you use spacers between the motherboard and the case mounts to stop electricity transferring??


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## PanamaGal (Jun 3, 2006)

It's a short. Try taking the motherboard out of the case and retightening the standoffs. Then put it back in, making sure the screws securing the board are tight.


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## Langos (May 4, 2006)

Yepp, ten spacers and 10 screwholes on the mobo! I'm starting to wonder if there is a short somewhere around the powerbutton/resetbutton.
Touching the chassie with anything conducting inside the red area will cause the computer to freeze, inside the red area and a few more places...










Edit: The computer is not grounded cause I live in an old appartment and the wireing isen't grounded except in the kitchen. I might have to try setting up my computer in there later. I took the mobo out earlier today and put it in making sure there are no extra standoffs that could shortcircut the mobo. No change.


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## Done_Fishin (Oct 10, 2006)

FIRST and MOST IMPORTANT... You are risking your life (& the life of any one who is living or visiting you) by running a bare metal frame with mains voltages inside it and NOT BEING EARTHED! If your only earthed outlet is in the kitchen run an earthed extension cable from that socket to the place you are using the Computer!

Secondly the lack of earth means that your system is susceptible to static electricity, which can not only cause the problems you are encountering but also cause permanent damage to any or all of the components in your PC.

When you mounted the mobo inside the case did you use Plastic spacers or metal ones under the mobo? They should have been metal and should coincide ONLY with corresponding holes on the motherboard where the screw head will make contact with a metalled surface , sometimes circular sometime square depending upon the whims of the board designer. At NO TIME should a screw go through a hole where there is no metallisation on the motherboard, ie the board would be bare.

Since I am unfamiliar with the box that you are showing in your photo , please explain what is hidden in those areas. I cannot see a power supply in the conventional position (top left hand side of the case as we see it in your picture) but I do note that power cables can be seen to be hanging there.


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## Langos (May 4, 2006)

I'm afraid I can't possibly run a cable through the entire appartment to the kitchen to earth my computer, it's over 50 feet through 4 rooms.
I used brass spacers when I installed the mobo besides the steel-ones already in place. The power supply is located in the lower back part of the case, here. The cables hanging from the roof are from a case-fan.








In the lower red are the harddrives and in the upper part of the area is empty but could hold internal 3.5" drives. 

Here is a picture of hardware installed in the case (not my hardware, pic taken from SweClockers.com - Nyheter)


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## Done_Fishin (Oct 10, 2006)

OK - you say that you used EXTRA spacers apart from those already installed in the case .. can you confirm that those spacers are in fact ALL in the correct positions and that all screws going through holes are in fact passing through holes that are metallised.

The fact that you insist that the freezing occurs when the metal parts of the disk enclosure meet the metal parts of the outer chassis seem strange since they should be at the same potential. Are you sure that you aren't twisting the box sufficiently to cause something else to come into contact with an area that is causing a short. According to what you say it seems like a certain type of action in a certain area causes the problem whilst a firm grp on the main area doesn't. See if a twisting movement between corners of the box make it happen too!


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## Langos (May 4, 2006)

All ten spacers are connected titly to a screw, I've checked three times. The computer is standing perfectly still and if I scrape my pocket knife against the areas marked with red the computer will freeze, sometimes regaining consiousness for a few seconds but only to freeze up completely a few seconds later.

I had an idea:
I have a Scyth Ninja 1000+ CPU-cooler and an Asrock DUAL VSTA s939 mobo and I'm thinking that the backplate used to mount the CPU-cooler is somehow connected to the mobo. The back plate is a X-shaped piece of metal with a adhesive layer on the side facing the mobo. There are some taps from soldering of capacitors trapped under the metal shaped X that could, possibly, be penetrating the adhesive layer making the CPU-cooler conducting...

Maybe that (ie if a capacitor is connected to the backplate) would explain why it's oh so sensitive to small differances in potential?

PS. I'm really grateful for all the help you're giving me! ray:


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## Done_Fishin (Oct 10, 2006)

I have found a picture of your cooler on new egg here
( Scythe SCNJ-1000P 120mm Sleeve CPU Cooling Fan/Heatsink - Retail at Newegg.com )
seems well recommended although maybe not well known.

I can't see exactly what you are referring to by caps and tappings but if you think there is a possibility of the fins shorting here then try adding something to isolate the possibility of a short to stop it from happening. However it doesn't really correspond to your original fault description. 
Whilst it is a possibility, the cans of the capacitors are rarely connected to either earth or a voltage these days, however that doesn't mean that they aren't interfering somehow with the way the PC is working.

You say that if you scrape a metal object on the area around the hard disk enclosure this causes the freeze up. Does this mean that you are holding the knife and just touch or must you apply some pressure?


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## Langos (May 4, 2006)

*It usually takes some pressure to make it happen but sometimes not... By the soldering-thing that I thought might be causing a short I meant something like this








which gets trapped beneath this backplate which is placed on the back of the mobo 







. 

I tried to remove the backplate to cut down the small piece of soldering that could possibly penetrate the adhesive insulating layer on the backplate but couldn't remove the backplate even with some serious force, I was afraid I'd trash the mobo.*

EDIT: I might have been right; read this thread silentpcreview.com | View topic - Scythe Ninja backplate issue? 
Question now is what to do? I should, ofcourse, not used the adhesive thingy but rather left the protective tape on and also cut down any soldering protruding through the adhesive insulation...


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## kodi (Jun 30, 2004)

I think you have solved your own problem.
You need to stop the metal pieces on the board touching the backing plate, you could try to take the backing plate off but that can be very dangerous and result in a damaged Mobo
Not sure of the clearance between the board and backing plate but can you get a cutter or file in there and reduce it


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## Done_Fishin (Oct 10, 2006)

There is info here
scnj1000
about how to remove the backplate, those are the pins of the CPU base that are sticking through the motherboard on the solderside of the motherboard.

The suggesetion is to use a hair dryer to warm up the heatsink, sufficient to break or slightly melt the glue backing but NOT too warm so that you damage the motherboard. Try shieleding the area around the motherboard so that the heat fall mainly of the metal plate. I don't undertsand how touching the drive area with a metal object affects this unless a lot of force is applied which distorts the motherboard sufficiently to cause the pins to short through the insulation. Once you remove this plate find an alternative method to mount a fxing plate underneath. Mention has been made of using the original motherboard mounting block.

Good Luck and keep us informed on your results.

I can't stress too much how you should NOT apply too much stress nor too much heat when trying to remove this .. but suggest that you find a way to heat whilst levering gently so that you'll understand when the glue starts to melt .. and then just keep applying the same pressure to lift whilst heating .. also "play" the heat around the area so that it all warms up evenly


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## Langos (May 4, 2006)

I'll have to find the original backplate of my mobo, hidden in some box in the storage room in the basement. Once I've found that I can try to remove the Ninja backplate. I've got alot on my plate at the moment so I dont know when I'll be able to do this but I'll inform with the results when I'm done. Thanks for all your help.


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## Done_Fishin (Oct 10, 2006)

Whatever you do , don't run that PC until you have sorted this problem, if there is something shorting through to that plate you risk burning out tracks in the motherboard by pulling too much current through them. The other point being that it can also damage the CPU or other semiconductors too for the same reason.

Good luck


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## Langos (May 4, 2006)

Ok, so I made sure the backplate doesn't short anything on to mobo by using a bitumen-sheet, roughly 1.5 mm think, as insulation between the backplate and the mobo. The problem, however, persists. I set up the computer in my kitchen where the power-thingys are grounded. The computer ran like clockwork for hours and no matter where I tapped it it never froze. Apparently my dad had an almost identical problem and changing his psu sorted it. He, however, has his comp connected to a grounded power-thingy which I dont. So I figured that if the same thing happens with another psu (with ground-failiur protection, which is probably what is causing this problem) then I know there is nothing wrong with the psu and it must be the mobo or just the fact that the power-thingy isen't grounded. Either way I have to hand my comp in to someone who can check it since I dont have a spare mobo nor psu. I'll return with the results of the checkup at the computer docktors.


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