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Question

Computer stuck in turn-on, turn-off loop

Aug 24, 2017 9:00PM PDT

Hey guys, I am having a problem with my computer that has me at my wits' end. Basically, one day I was installing a required update for Windows 10 and my computer froze and then turned off. I turned it back on, but it only stayed on for a few seconds, then shut itself off, turned on, then off again, and so on until I finally pulled the power plug. So I took apart my computer, and started it with just the cpu, mobo and psu attached. Worked fine. I kept adding pieces one by one and they all started up just dandy until I got to the ram. Plugged a stick of ram in, and bingo, back to the infinite loop of death. In fact the computer runs just fine with everything but the ram plugged in. Great, I naively thought, I just need new ram. So I bought new ram, plugged it in and... same issue. Now I am really kind of at a loss. I tried clearing the mobo's CMOS, and that did nothing. I checked to see if the cpu wasn't seated right or something. Looked fine. Now I am wondering if it is something wrong with the ram slot on the motherboard. Maybe it got fried somehow? Help?

Discussion is locked

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Clarification Request
Let's hear all the make and models in play.
Aug 25, 2017 9:11AM PDT

Also, do not attach any drives. We only want to see if the machine stays up and not failing to boot and rebooting which is another issue.

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Answer
Start with
Aug 24, 2017 10:25PM PDT

Psu+mobo+cpu/hsf....test.....nothing else connected or plugged in.

If that works add a stick of ram...test.

If that does not work move the mobo to a piece of cardboard....test.

If it still does not work and you've tried different ram and slots then your down to 3 parts.

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Tried that.
Aug 25, 2017 8:17AM PDT

I have done all of that already. It starts just fine with just the motherboard, psu, cpu with hsf. It works with every component attached except the ram, so something with the ram is the problem. I have tried one stick of ram in both slots, nothing. Bought new ram, did the same thing, and still no luck.

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Answer
A few thoughts ...
Aug 25, 2017 7:41PM PDT

Before we get analytical, let's just look at one possible explanation that you don't seem to have considered yet: Sometimes a power supply unit is "flakey" but isn't too obvious about it. In your case: Until you add RAM to your setup there can't really be any attempt to go through the BIOS self tests. Up to that point the PSU may keep up appearances and seemingly do its job. But once the RAM is added, more power will be drawn and that alone may tip it over. If not, the self tests are started and power requirements will go up a bit in the course of that. When the PSU senses that more power is requested than it can supply it will shut down and after a short while come back to try again - in a working PSU this behaviour would be quite suitable in order to to catch, for instance, a hard drive (or any other component, really) that has a short circuit and draws more power than it should. So, unless your RAM (old as well as new) is faulty in that way (unlikely) we would be looking at a PSU that keels over as soon as it needs to supply any non-trivial amount of energy.

Now, in analytical mode, we would be looking at the "beep codes." During the self test, the BIOS will use the speaker to indicate via a sequence of beeps which test failed. The mobos I have seen in recent years had a built-in mini "speaker" capable of not much more than to emit these beeps, but to be sure you can ylways connect a small speaker to the corresponding pins on the mobo. Then if you do hear a sequence of beeps during this process you can go and google your way to an explanation - the codes vary by BIOS version, so you need to research this a bit. There is, by the way, a beep code for "missing or non-working RAM."

Once you have a position on the state of your PSU (try things with a borrowed replacement if you can) and/or any beep codes you may not be able to interpret, come back here and we'll look further.