Magnetized Computer Cases

A magnetized case will affect hard drives long before it will impact the motherboard.

On the case you are having problems with, you likely have one of the following issues:

Standoffs are too short, and the leads on the bottom of the motherboard are shorting out against the case.
Look closely at the case and the bottom of the motherboard. The standoffs should be just under 1/4" tall, and less than 3/16" across. Check for any area where the case may be too close to the motherboard.

Standoffs are too large or improperly positioned, and are causing the motherboard to short out.

The motherboard requires ground to be isolated at 1 or more standoff locations where you now have metal standoffs.
Check the manual for mounting instructions.

The standoffs are too short, and the AGP card cannot fully seat into the AGP slot.
(this happens a lot with inexpensive cases)
When I suspect this problem, I remove the metal bracket from the video card, and see if it inserts farther into the slot.

The power supply has a wiring problem, and a ground loop is formed between the power supply and the case.
You can try insulating the power supply from the case to check this. If it now works, get a new power supply.

One of the ground tabs for the I/O shield may be getting inside a connector and causing a short.

Chas

ans 1 is correct. Adding that I have had to use plastic standoffs with plastic screws to solve the problem. Plastic standoffs with "snap" ins also work. Had one MB I had to shim away from slot side where it touched the case.

Make sure you did not install extra standoff(s) that might be contacting the motherboard underneath. This most likely would short out the motherboard.

Well will the case attract a pin or paper clip, sligthly or otherwise? Magnetized case causing a problem is a hoax. The answers so far are very good ones. Observation first is the way to go. Make sure nothing is touching anything it should not.One other probability is; when bolted to the case the motherboard is being stressed in such a way so that it exposes a defect in the board itself. Example, if the board is not an exact fit to the case then you may slightly bend or stretch a section of theboard causing a small existing fracture in a section of the "land" (the foil interconnecting roads seen on the circuit board)to separate. Closing again when you remove the board. Another possibility is EMI. Computers are very susceptible to EMI because every wire and every circuit-board land acts like a little antenna, which can drive microprocessor controlled equipment NUTS! The wiring associated with the particular cases may be part or all of the problem in generating this "noise". I presume that these cases are prewired? So you may want to investigate the routing of this wiring and the fidelity of the power supply itself. You could take voltage readings at different points on the circuit board (try to record all the voltages, 12, 5, 3.6volts etc.) in the case it works with then put the board in the case it will not work and check the same points for these voltages. That should tell you something. You may find a voltage missing or lower than it should be.You can also check continuity (with the power off!)at different points in one bad case then check in the working case. This assumes you have the skills to interpret your findings. Anyway this sounds like a fun hands-on problem to tackle! There are a ton of things to try and tocheck!