Problems related to Motherboard

Running the motherboard without a case is a common technique used by technicians to eliminate any weird grounding and shorting issues or mechanical stresses. It also makes it much easier to swap the CPU if that's required. I normally do my bench testing on top of a cardboard box, with a static free bag or foam between the bottom of the motherboard and the cardboard. You don't walk away from a test like this or you might come back to find the box on fire! If your motherboard powers up on the bench with the same power supply that you used in the case, you have a geometry problem.
Ideally, you should have a spare power supply for bench testing if you're going to do regular repair and testing work. Make sure some standoffs aren't higher than others, putting unacceptable stress on the motherboard. Check that every standoff appears under a screw hole. The easiest way to be sure is to count the standoffs, count the screws, and make sure there are no screws leftover after you install the motherboard. There could be a short caused by a misplaced standoff, a loose screw, metal chips from shoddy materials. I've encountered standoff shorts that produce an endless string of beeps like RAM failure, without damaging the motherboard. There's also the possibility that the case geometry is so messed up (out of square or level when the cover is forced on) that it's putting an unacceptable mechanical stress on the motherboard resulting in an open circuit. If you can't find the cause of the problem, don't hesitate to try another case and power supply.

How to Replace a Motherboard (Removal)

The first step to replacing a motherboard in a desktop computer is to remove the old motherboard. That may sound trivial, but it's literally half of the job, and I'm splitting removal and installation onto two pages so it doesn't get too big. In order to remove the motherboard, you not only have to disconnect all connections between the motherboard and components in the case, you should also remove any cables that are simply in the way. Remember to touch the metal edge of the case to ground yourself from time to time. Some techs like to leave the power supply plugged in for a ground, but that's pretty crazy with ATX technology, since if the switch on the back of the supply goes on, the power supply will be live. I unplug the power supply and avoid dancing on the rug to generate static electricity. We start by removing the 1x4 power connector from the hard drives.

Next we remove the data cable from the hard drives. In a larger case, I might have left the data cables installed on the drive end, but there's very little clearance between the motherboard and the drive cages, and you don't want to start wrestling the old motherboard out because you didn't prepare properly. It's just like working on a car, if you don't get enough stuff out of the way to have room to get a wrench in and see what you're doing, you're just wasting time in the long run. Keep in mind that we're replacing the motherboard, not just taking the old one out, and you don't want to bash the new motherboard around as you're installing it.

 Now it's time to remove the PCI adapters and the video card. All of the adapters that mount in motherboard slots are secured to the back rail of the case with single screw each, though the screws are often missing in systems that have been worked on. You may as well take all the

screws out at the same time and put them aside in a glass or any other small container to keep them from getting too lost.

You should always handle adapters by the the edges and by the metal bracket when removing them from the motherboard. Again, you can't race through this part like you're just waiting to get to the main course, because you're going to need to put all these adapters back in after you replace the motherboard, unless the new motherboard has those features integrated in the I/O core. You should especially avoid touching the gold contacts on the card edge that pulls out of the motherboard slots, because the oil from your fingers is an electrical insulator.

Standard ATX motherboards feature a single 10x2, 20 pin connector for the power supply. The  connection  features  a  sort  of  a  simple  latch  which  is  released  from  the  nub  on  the motherboard connector by depressing the top of the latch (just below my thumb). You can also see the nub on the motherboard connector, on the side near the motherboard edge. It can take a bit of force to pull the connection out of the motherboard even once it's release, since there are 20 tight connection, so be prepared to use your off hand to hold the motherboard down if the edge lifts as you remove the connector.

Now we get to removing the data cables from the old motherboard. If we had more room in the case, I would have left them attached to the drives on the other end. If you have trouble remembering where everything goes when you go to install the new motherboard, I'd recommend the book I write for McGraw-Hill, "Build Your Own PC," which uses extensive photographic illustrations to detail the complete assembly of three state-of-the-art PCs. Note that I'm using both hands to pull out the ribbon cable, holding it as near to the connector as possible. High quality ribbon cables often include a pull loop or tab so you can remove them without stressing the cable.

The motherboard is actually mounted in the case with a series of screws through the motherboard, seven in this case, all of which must be removed. About the worst thing that can happen when you're replacing a motherboard is that one of the screws will turn and turn without releasing. Normally, this is due to the screw having been over-tightened in a brass standoff, which comes unscrewed from the motherboard pan and remains attached to the screw. If you think this is happening, proceed to removing the rest of the screws first so you won't place undo strain on the motherboard by flexing it up. If the standoff thread in the motherboard pan is stripped, you can take off the other side of the case and grab it with vise grips from the back.

The final set of connections we have to deal with are the front panel leads that attach to the motherboard. This includes the LEDs for hard drive activity and power status, the case speaker, and most importantly, the power switch. ATX systems use a logic switch to tell the motherboard, which is always receiving a trickle of power from the ATX power supply, to power full on. These are all small format connectors that easily pull off, and frankly, the power switch is the only one you really need to reconnect when you replace the motherboard, the other's are bells and whistles.

Once all the connections to the motherboard are removed and the screws are all out, you can lift the motherboard a little and pull it away from the back of the case, where the connectors of the I/O core protrude through the shield (left). Once you disengage the I/O core, you can lift the motherboard right out of the case. I usually hold onto a PCI slot and the CPU heatsink, there's just no room to get your fingers on the edges of the motherboard in most cases (below). That pretty much covers the removal phase of replacing a motherboard, so skip over to how to install a new motherboard if you're ready..