I have a Compaq Presario SR1522X Desktop. It began to shut down intermittently now it won"t even come on. When I press the "On" button, the fans will turn over once and shut down. The green power light on the back of the transformer goes out. After about 10 seconds, the green light comes back on but goes out when I push the "On" button. I have plugged in and unplugged the power cord many times but with no result. Could it be the power supply?
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Yes, the power supply is always the most likely candidate for such case, and maybe 9 times out of 10 it's the problem.

However, if the computer is not connected via a UPS battery backup type unit, it becomes more likely that a second case is the issue, namely the motherboard is dead.

However, since that's basically the end of the machine for all practical purposes, we always prefer to test the power supply with a new, known good one, first, before making any further assumptions.

Some name brand computer makers use non standard sizes for their psu (power supply unit), which makes what would be a trivial swap non trivial. This varies by make and model so there's no way to know for your machine. But generally the psu should be standard size.

I like, for value and quality, the thermaltake series, keeping in mind there's no need to get a lot of watts, just get one that roughly matches, ie, the cheapest ones usually.

However, it's not a good idea to buy new hardware until you have verified the source of the problem, that can just lead to spending money you didn't need to spend, so by far the best thing to do is find another power supply, borrow one or something if you don't have one, that is matched at least for your installed ones watt output (it says on the side of the psu how many watts it outputs), then swap them, see if it starts up, if it does, great.

Check the Connections First!
Even easier, to make sure it's not the connectors corroded. Before you do any of the power supply replacement testing though, make sure to unplug and then replug a few times the 1, 2, or 3 primary connectors from the psu to the motherboard, especially the big rectangular one that has either 20 or 24 wires. They have little clips that hold them in, you have to press that in or out with your thumb to remove them.

There might also be a 4 pin connector, square, usually yellow/black wires, going into the mobo close to the cpu, depends on the age of the mobo and cpu though, older ones don't have this. It also has a little clip holding it on to the connector.

Also unplug and replug that one.

If this isn't something you're comfortable with, find a reasonably tech savy friend who can do this for you, it's not hard, but does require some familiarity with the innards of the box.

I've seen where unplugging then replugging the connectors made it work a few times, then fail again. If this happens, your psu is certainly almost dead, and needs to be replaced.

Standard Power Supply Unit (PSU) Dimensions


Generally the length, front to back, doesn't matter, but the width and height do, that's what will determine if it fits into the case as expected or not.

standard mounting screw configuration is 4 screws, 3 on corners, and one slightly inset from corner.

All standard psus are, well... standard. Though it does matter where their cooling fan is,some are on the rear, some on the bottom, and some on top. That corresponds to various types of cases.

You would certainly not be using the top one with a compaq I believe, unless compaq has suddenly decided to produce high end machines.
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