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July 21, 2016

Replacing a Power Supply

Filed under: Main — Tags: , — admin @ 12:01 am

After two days, a new 500W power supply was delivered to my abode. My son and I took no time to install the beast into his PC. And right away we noticed that the new power supply featured a larger fan. It looked more efficient. If heat was causing his PC to restart, then the new power supply might help.

To replace the power supply, you first disconnect the power (duh) and open the PC’s case. Figure 1 illustrates this important step.

Figure 1. Safety first! Disconnect the power.

Figure 1. Safety first! Disconnect the power.

The power supply is the most-connected thing inside the PC; it has more cables than the motherboard. To remove it, you must disconnect all the power cables, then unscrew the power supply. Like everything in a PC, it’s modular, so after the four screws on the rear of the case are removed, you pop-out the old unit and plug in the new one.

Figure 2 illustrates the mess of cables. Each one must be disconnected and you have to remember where they go. The locations are the disk drives, the motherboard, and on my son’s PC, the video adapter.

Figure 2. The mess of power cables inside a PC console.

Figure 2. The mess of power cables inside a PC console.

Qe removed all the cables and popped out the old, 350W power supply. Then I inserted the new 500W power supply and reconnected almost all the cables.

Yes, I forgot a cable. It happened to be to the PC’s primary hard drive. That was an obvious error because the system didn’t start. So we powered-off everything and reconnected that cable.

The system ran fine for a while. Then we smelled ozone.

I had my son turn off the PC. It was blisteringly hot.

At first I blamed the power supply. It could be defective, so I removed it and replaced the original, 350W power supply. The ozone smell didn’t return, but still his PC kept resetting.

I took the 500W power supply and ran it independently. You can do so by shorting two of the motherboard wires (the green one and any black one), which is a trick a grizzled PC hardware veteran taught me. I ran the 500W power supply for a few hours and it never got hot or smelled like ozone. That left one, final culprit for my son’s PC crashes: the video card.

My son installed a temperature monitor and kept track of how hot the PC and the GPU (graphics processor) got while he ran a game. It was amazing: The GPU ran a fever of 98° C, near the boiling point of water. The monitor software also showed that his graphics card was maxed out on memory.

It turns out the graphics card has only 1GB of RAM. To supplement, it borrowed memory from the motherboard and all that swapping for a high-end graphics card was heating up the system to the nth degree. My guess is that the graphics card has a host of pregnant capacitors as well. That’s apparently what causing the system to overheat.

We ordered a new graphics card and it should arrive by the next blog post. I’ll update you as to whether that replacement solved the restart problem.


  1. Hmmm, might be worth taking the Card out and looking over the capacitors, if they are tatenlum (square blocky types with + on one end) the electrolyte if it has been over temped can boil and distort the case if thats happened and it was bought seperatly from the PC you might be able to return it with the ‘component failure’ diagonis. The other common fault is if the board bas over heated for a long time some of the BGA components can come unseated, again a ‘componet failure’ and might be covered. Bit of bother but it miight be worth while…

    Comment by glennp — July 21, 2016 @ 2:24 pm

  2. The story gets more and more mysterious as we explored various options. I really wish for my son’s sake that the problem had an easy solution. He’s very frustrated.

    Comment by admin — July 21, 2016 @ 2:32 pm

  3. Know the feeling!!

    Comment by glennp — July 21, 2016 @ 3:43 pm

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