How to find & fix motherboard shorting with the pc case?

[RFMattos]

Can somebody please helpme, I had a problem with my new computer, when I just got it I opened the case (breaking the sealing sticker and thus voiding the warranty) and installed my old CD RW and SATA hard drive. After that everything worked perfectly for three days. Then one day I turned it on and went on with my bussiness but out of nowhere it just went dead. It was really weird because it didn't turn on anymore, so I went crazy traying to find a cause for the problem until I found it.

I strip it all apart and bech tested it and it WORKED PERFECTLY AGAIN. so I put it all back together and again no signs of life. So I bench tested and again worked perfectly. I discarded all other causes of failure since I bought a brand new power supply. I tested it outside first with only CPU, CPU fan and ram stick then added the hardrive and CD RW and worked perfect. So the problem only presents itself when it's mounted on the case. The standoffs are all properly aligned and not touching anything they shouldn't, so is the IO panel.

The mobo is a Biostar GF8200C M2+ with a AMD Sempron 140 processor, 1 GB DDR2 Kingston Ram, Western Digital Caviar 250 SATA HD, Generic 350W. Power supply.

So could anybody tell me how the hell find where the problem is and how to fix it?

 

[T_T]

Start with everything in and hard drive only. If the system boots and displays POST, you can rule out where the HDD is installed. If not, try mounting the HDD someplace else, or leave side panel open (just to test) and let the HDD dangle w/o touching the case.

If the HDD isn't the issue, move on to the CD-RW. Ensure that there aren't any frayed wires/connectors. Ensure that the drive doesn't touch the mobo. Lastly, ensure that there aren't any wires touching the enclosure of the CD-RW.

 

[RFMattos]

Start with everything in and hard drive only. If the system boots and displays POST, you can rule out where the HDD is installed. If not, try mounting the HDD someplace else, or leave side panel open (just to test) and let the HDD dangle w/o touching the case.

If the HDD isn't the issue, move on to the CD-RW. Ensure that there aren't any frayed wires/connectors. Ensure that the drive doesn't touch the mobo. Lastly, ensure that there aren't any wires touching the enclosure of the CD-RW.

Thanks for the answer, but the thing is that it doesn't even show any signs of life just with the mobo alone inside the case, but when I put it outside it works perfectly even with all the periferals conected. I've read that the mobo can also get grounded by the standoffs and the IO panel and that it's ok. But how is it that if I put the mobo inside the case properly it doesn't work at all.

 

[T_T]

When you built the system outside of the case, did you connect the case power switch and use the power button? or did you jump the mobo power switch pins?

If you did use the power button while the system was breadboarded, that rules out a short in the power button switch and then I would replace all standoffs at this point to rule them out.


Also remove the I/O plate to rule that out.

 

[RFMattos]

When you built the system outside of the case, did you connect the case power switch and use the power button? or did you jump the mobo power switch pins?

If you did use the power button while the system was breadboarded, that rules out a short in the power button switch and then I would replace all standoffs at this point to rule them out.


Also remove the I/O plate to rule that out.

When I tested it ouside the case I didn't use the power button but I didn't use it either when I put it back in the case, nor did I install the I/O plate, and I even put some electric tape on top of the standoffs and that seemed to work but as soon as I put one screw in the mobo would not turn again.

When secured by the screws I use an old multimeter (not digital) to check for continuity (ohms) between parts of the mobo and the case, and even the batery had some. So far I'm lost

Anyway thanks for your help so far...