How can I tell if my Power Supply is Dead?

[lutherl]

I have a Dell (Already not a good sign) Optiplex 755 SFF that i've been having some issues getting to power on. The power supply can handle up to 280W and works well most of the time. Occasionally, the computer will not power up, but has never cut off while in operation, which confuses me. I can turn the computer off, but when I turn it back on I get a blinking orange light, which indicated either a power supply or motherboard failure. I've checked the capacitors and general condition and both seem to be in tip-top shape with no bloated or oozing caps. So here are my questions:

1. I have an ATI Radeon HD 4350 graphics card inside that takes 174 watts, would this be causing a problem?

2. Why would the power supply refuse to operate only when trying to restart and not cut off while running?

3. How can I test the power supply (using a computer application) to see if there are problems?

The Dell is running fine right now on Windows 7 Professional x64. Let me know what I can do.
Thanks! - Luke

 

[Darkbreeze]

You can read this, apply the instructions to download HWinfo and then look at the system 3, 5 and 12v sensor readings. Or you can go into the bios and if it has that feature you can look at the values there.

http://www.tomshardware.com/faq/id-2583515/basic-troubleshooting-layman.html



The best method though is to test it manually.

https://www.youtube.com/watch?v=ac7YMUcMjbw

 

[Dark Lord of Tech]

http://support.antec.com/support/solutions/articles/1000015319-is-my-power-supply-dead-the-paperclip-test
Is my power supply dead?: The Paperclip Test

 

[Darkbreeze]

http://support.antec.com/support/solutions/articles/1000015319-is-my-power-supply-dead-the-paperclip-test
Is my power supply dead?: The Paperclip Test

Is this useful for a power supply that we already know powers on, and just doesn't start the system sometimes? Since the system apparently does run, I'd think a manual test would be of more help for checking for a weak unit rather than a fully dead one.

 

[lutherl]

Yeah, the paperclip test was successful, but the power supply still cuts out at times. I've removed the video card in case it was taking too much energy, but it keeps powering off. I just took the power supply to a professional and he found out that all voltages were within 0.1v! I ran the Dell extended BIOS test and all hardware passed, so i'm really in a pickle.

 

[Darkbreeze]

Did he test static voltage or did he test the unit while it was under a full load, on each of the individual rails? Plenty of power supplies that can pass muster with no load applied but drop out quickly once there is a load or the unit gets warm. Your best bet is probably going to be to swap in another power supply and see if you get the same behavior.

To me, it sounds like it almost certainly has to be either a bad power supply or motherboard. One other item I've seen cause similar issues though is the CPU. If you have any bent pins on the CPU or motherboard, depending on what socket style you have, the system COULD still operate, but display a variety of issues and problems from not starting/POST at all to pixelated displays or anything in between. Have you had the CPU out of the motherboard at any time in recent memory that could possibly have resulted in a bent pin when reinstalling?

If not, then I'd be focusing on the PSU or motherboard. If you swap out the PSU for another known good unit that has sufficient capacity and at least decent quality, and still have the same issue, then it's probably the motherboard. Could be a RAM issue as well although that's maybe a little less likely. If you have multiple memory modules, try removing one of them and see if the problem is still there. If it is, swap it for the other module and recheck.