I just bought a new desktop computer Dell Vostro 3671. When I plug the AC power cable, it turns on for about 2 seconds then off (the computer is new and it was shipped to me like this, I didn't make any changes) although the computer runs ok with no problem, I was concerned about this as I've never experienced something like this with any other device. I tried looking on BIOS setup if there's something and I tried running the diagnostic, everything seems fine. Is this normal ? btw I noticed there's a little button on power supply near the LED light if this could help with something ?
In my opinion, (almost) every Dell desktop computer has this kind of behavior when you connect its AC power cable.
You can set the 'After Power Loss' setting in the BIOS (or UEFI) in 3 different states :
- On (computer turns on when connected to AC power supply)
- Off (in that case, the computer turns on for about 2 seconds and then turns off again)
- Last State (this option remembers the last state, either 'on' or 'off' just before it was physically disconnected from the outlet)
Personally, I prefer the state 'On' because all plugs are connected to an extension socket which already has a power switch. That way, I have to touch only one button which turns on the whole system.
His description of normal operation would indicate that it is only during initial connection of the power cable. At first I thought the description was contradictory.
I've seen this characteristic in some computers. What the OP is describing is a brief power cycle when the power supply is connected to line power. There's a bit of power supply fan activity, then all noise is terminated. I've never checked to see if the CPU fan or other internals power up then off during this sequence, as it's not caused problems later.
Some older computers will sometimes begin a complete power sequence when the cord is engaged, but it can be terminated by holding the power button in until it shuts down. Somewhat related to this question, but not precisely.