General Problems Related to Loose Connections

Explanation: It is suspected that there may be a loose connection, shorted component, loose memory modules, or other physical problems within the PC.

Diagnosis: Any time that the PC is opened up, worked on, or moved, there is the chance that a cable or component has come loose, that something has been moved and is now where it should not be, and so forth. Loose components and similar physical problems can cause a host of bizarre situations that may seem to imply failures of unrelated components. For example, I once had a floppy drive stop working after I upgraded my system RAM; it turned out I had loosened the floppy drive cable, whose connector was directly above the SIMM sockets on the motherboard.

Recommendation: At any time that you suspect that a physical connection problem may be responsible for erratic system behavior, turn off the PC and disconnect the power cord from the power supply. Then go through this checklist:

• Make sure that there are no loose screws or other components inside the case. These can cause shorts and other serious problems with the PC.
• Examine the inside of the box for any cables or wires that are very tight. A cable that has too little slack on it is a prime candidate for being loosened accidentally, or even being damaged. A cable pulled out by accident can also damage one of the devices it is connected to. Make sure no cables are being pinched or twisted harshly. Check any taut cables for damage or loosened connectors. If possible, rearrange component locations to loosen the cables up.
• Ensure that there is no physical interference with devices that have moving parts. Some common problems include: cables getting in the way of the CPU fan, causing it to not run or to make noise; cables being pushed inside the mechanisms of floppy disks; drives that are mounted too close to each other that may interfere with each other; cables being pinched between components; cables or wires getting in the way of the power supply fan or intake vents; and expansion cards interfering with motherboard components.
• Check the mounting of the motherboard. It should not be possible for the motherboard to contact the case in any way. Lightly press down on the expansion slot area of the board to test how much it flexes under the pressure of inserting expansion cards. If the board flexes a great deal or contacts the case under this circumstance, it is not properly supported.
• Make sure that any screws that have been used to mount the motherboard are touching only the metal pads designed for them on the motherboard. If there is any chance of the head of a screw contacting a wire on the board, the screw should have a paper insulating washer inserted under it. Make sure that there are no "extra" metal standoffs contacting the underside of the board.
• For a system with the power button on the front, examine the 4-wire electrical cable running from the power supply to the front of the case. Make sure it is not damaged, twisted or pinched. Ensure that there are no loose or bared wires.
• Double-check all connections between the LEDs and switches on the case, and the motherboard. Ensure that none have been pulled loose. If they have, reconnect them, making sure to do so the right way.
• Double-check the power connections from the power supply. Make sure the connector(s) to the motherboard are inserted properly and have not come loose. Check the connections to all the drives in the system and the CPU fan, if applicable. Make sure any unused four-wire power connectors are tucked away and not touching anything.
• Double-check all the data cable connections to the motherboard, and to the devices they go to as well. Make sure the hard disk, floppy disk, serial port, parallel port, and other connections are all securely in place. Look carefully, because it is easy for these cables to become partially disconnected, which causes all kinds of very bizarre behavior. Make sure that cables connected to headers on the motherboard are connected correctly and aren't "off by one" pin. Make sure that the correct IDE port is being used on the motherboard for the hard disk.
• Examine the processor. Make sure the fan is securely on it. Make sure that it is not loose in the socket/slot; it should be inserted all the way into it. You may want to loosen and reinsert the processor.
• Examine the memory SIMMs or DIMMs. Ensure that they are all seated correctly. Gently rock them to make sure they are secure. You may want try removing and reinserting the memory if you suspect a problem related to it.
• Ensure that all expansion cards are seated fully into their slots and are not interfering with any part of the motherboard.
• If this is a newly-built PC or a major upgrade, you may want to look at this section for more common hardware problems associated with new systems.

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