Replacing a PC Power Supply

Beautiful day here yesterday but I spent part of it wrestling a new power supply into a desktop pc. The PC wouldn’t turn on this morning — didn’t respond at all to the power switch and there were no lights on in the case. Power supply seemed like a good bet as the culprit.

So the steps to replace and my tips:

* Unplug the PC! You don’t want to mess with live power or the residual power that may be lurking in your supply.
* Disconnect all the LAN, monitor, USB, SATA, Fireware, speaker, mike, etc cables. Remember what goes where! Sometimes I label the cables so I can remember. Oh and this guide to soundcard ports will help you down the line.
* Remove the side panels or case housing from the pc. You are going to end up with lots of loose screws — make sure you have a plastic bag or something to keep them in, and that you can remember what screw went where. For my PC case I had to remove the side panels and the top panel and I ended up with 4 big thumb screws for the side panels and 4 small machine screws for the top panel.
* Now that your case is open, you might as well vacuum it, you probably have accumulated a lot of dust. Make sure to get around the fans and all case seams. Oh and hopefully you followed the guidance in the previous step and bagged all your screws — there is nothing more annoying than vacuuming up all your loose screws accidentally.
* Unscrew the power supply. In my case I had to remove screws holding a decorative plate onto the rear of the supply, and remove the screws holding this plate to the case. Then the plate could be removed and the power supply could be easily slid around.
* Without disconnecting all the power cables in the case, lift out the power supply. Examine it to determine what wattage it is. In my case it was a 500W supply which seemed a little tiny for a tower machine with a good graphics card. Additionally, trace all the power cables leaving the supply and make an inventory of all the connectors you are using. This is probably overly anal, but you want to make sure your replacement supply has all the right connector types in the right quantity. Unless you have really maxed out your machine, you will probably not have a problem.
* OK this step is not necessary at all. But I wanted to confirm that my power supply was indeed the culprit. So i located the four small machine screws on the bottom and opened it up (voiding the warranty per the label). On examination of the interior, sure enough there was a charred capacitor that had scorched the board it was mounted on. Pretty obviously blown. Perhaps a braver soul than me would just try to replace the capacitor but this doesn’t seem smart to me.
* You know now the minimum connectors you need and the minimum wattage supply you need. Go to your local PC supply store (in my case Fry‘s) and buy a replacement. I went up to 700W and got a thermaltake. No idea if this is the best choice but Fry’s had a ton and the box was very descriptive about connectors supported. I was intrigued by the cable management series of power supplies which seems like to might reduce massively all the excess cabling in my PC but I need to learn more about.
* OK now replace cable by cable — disconnect the cable leading from the old supply to a port, and snake in and connect the cable from the new supply. I do this connection by connection so that I remember them all. And make sure you snake the new cables along the same path as the old, so that everything fits in when you eventually close the case up. And of course seat your connectors well, some of them need a bit of force (though if you have correctly aligned the connector it shouldn’t be that much force)
* Once all the cables are disconnected from the old power supply, put it aside. place the new power supply into the case on the rails where the old supply sat.
* Before reassembling the case, test! Re attach all accessory cables and attach your power cord and power up the system. Does it boot? Do all drives and accessories work? Hooray, ours did on the first try.
* Put the case back together
* Recycle the old supply

OK takes way more time than it should and it is an amazing mess of cables inside a PC case. Man it would be cool if there was a simpler power bus inside the case.