A curious MB problem with the power supply...

[mauro]

My asus CUV4x board will not power on when the switching power supply is properly mounted and screwed in the computer chassis. Under these conditions, the computer will simply not power on. The board is apparently initiating a "short" to keep power from the board. However, if the power supply is removed from the chassis and placed on the side without any physical contact to the chassis, the mother board starts with no problem. In fact, any kind of physical contact with the chassis causes the board to "short" or fail to start. The computer case/chassis has housed numerous Motherboards in the past, and never presented any problems whatsoever! Is there a remedy to this situation, possibly a workaround to more effectively shield the board from the power supply. I should add that this condition only causes a short during power up. If you put the power supply back into the case after the system boots up, everything is fine, i.e., there is no power down, loss of power, etc.

Any suggestions, solutions (other than a new case, again, the case works fine with every other board I put in it).

[jmorrell]

Sounds like the motherboard is grounding to the case. Try remounting your motherboard. Either put fiber washers under the screw heads or use nylon mounting posts to prevent the board from shorting on the case. You should be able to get either at your local computer store if you don't have them.

[mauro]

Thanks for quick the response! I do have grounding problems in the house. I moved here six months ago and learned that half the house outlets are not properly grounded. An electrician will take care of the matter within the next month. However, none of my other boards (I put in about three in this case), and none of the other computers in the house (I have four others networked) produced any grounding/electrical problems at all. To ensure some grounding until the outlets are secured, I am running a copper wire connecting my metal heating baseboard to an earth ground outside. All the computer chassis are grounded to the heating baseboard in this fashion. I considered the possibility of metal contact in the chassis and applied electrical tape to the screw holes and made sure that along with the stand-offs there was no physical contact with the board. I am somewhat perplexed. The power supply MUST be outside the case, and even after powering on this way, I can put the power supply back in the case (carefully, of course), mount it and the board operates flawlessly with no interference. It's only during a cold boot that the power on failure returns. I have also tried several other options such as disconnecting my own ground, grounding the cover of the power supply, etc. Still the same problem. And yet all other boards (SOYO, AOPEN, LUCKYSTAR) powerup and operate normally.
Hmmmm