OPTIPLEX 390 Shutting off

Hi @kilime ,

You may try replacing the power cord and change to another power plug for further diagnostic. If no improvement, it goes to PSU or motherboard in most cases.

Besides, I find this in ebay, a 240w PSU with list price at US$0.99 and able to ship within US. May worth to try making an affordable offer and see if the seller accept.

Hello, Before we dig in to the possible solutions I want to ask you something. You stated that you came home and it was completely off so I imagine you leave it on a day or two and shutdown it the third?

One thing you can do is that you can remove all sticks of you RAM you have and start it, does it give any sound indications or does the led behind the power button change from shutting of to flashing?

Another thing you can try is to remove all cables (motherboard, hard drive e.t.c.) and leave only the motherboard's, cpu's and the power button's connected. Does it behave differently?

It seems like it's a short circuit of some kind. A flashing red power button indicates motherboard and cpu error so the motherboard error is out. The only thing that remains is the PSU.

Best of luck mate.

im currently working on on a dell optiplex 390 with the same issue the solution the power button you have to change it in order to fix the problem.............try plugging in the power cord disconnect the power button then connect it and disconnect it back it will stay on 

Hi, what do you mean by your statement "try plugging in the power cord, disconnect the power button, then connect it and disconnect it back, it will stay on" 

I got confuse with your instruction. 

In any case, I am having somewhat similar issues, on a hand me down Optiplex 390. 

Sometimes, it will shut down even before the OS Loads, sometimes, after few seconds or minutes after the Windows 10 load, sometimes, which is very rare, like now I am using it for about an hour now. 

I have remove cables, memories, etc. and re-install them and yet the issues remain. 

Now am not sure if my Power Supply Unit is the issue for this is the second time that this Desktop works for at least an hour the last one week. 

Advice and recommendations please. On how to check my Power Supply maybe or other issues?

Thanks

Re: how to check my Power Supply maybe or other issues?

could be psu failing slowly.  try a spare working 24/4 pin psu and see if it make a big difference.  If still the same shut down, then try remove both memory sticks and test each one in PC by itself (only install one memory stick at a time) to isolate individual memory issue.