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Last reply by 08-16-2021 Unsolved
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2 Bronze
2 Bronze

diagnostic lights and noise just plugging the power cable


I have a Dimension 5000

When I plug in the power cable into the mains (without pushing the button to start it) the PC seems to perform a check : diagnostic lights on, and a fan noise that lasts 1-2 seconds. Do certain components receive power anytime the computer is connected to AC power?

Is it better to leave the PC plugged when you are not using it ?

Thanks in advance for any kind of help


Replies (5)
3 Argentum

this kind of behaviour should not be seen with any electronics devices after plugging the power cord without pressing the power button.
could you post the color combination of the four LED lights at the back and the color of the power button?
2 Bronze
2 Bronze

I've got the same behavior with my XPS Gen 3.

I didn't have a look to the four leds inthe back.
The power button is normal --> no green light.

ps : You can see that there is a lit green LED on the mobo.
6 Indium


The system uses what is known as a soft off.  Anytime the system is plugged in, there is a minimal amount of electronic activity in the system. 

You can leave the system plugged in all the time, except during storm or when adding removing components. (When adding RAM for example, unplug, then press & hold the power button for 5 seconds to discharge any stored power in capacitors on the MB, then add the RAM)

Donald K

Inspiron E1505 Windows 10 / XPS 10 Windows RT

Dimension 8400 Windows 7/8



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2 Bronze
2 Bronze

Thanks to you all for your advice. Finally I got an email from Dell support (I am in Brussels) telling me that it was normal behavior if after starting the PC everything was fine?!

I will keep it plugged even If I do not use it for several days …

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