What do you mean?? dont understand.. you mean you try other power point it is not working??? or you try power surge it is not working?

The computer does not power up when the power switch in the front of the computer is pushed.

There is a round button on the back (on the power supply, just above where the cable is plugged in).
That round button AND the power switch in the front have to be pushed together for the computer to boot up

Ok! simple since it is new dell you can call their support to check for you and i think is free..

they will solve your problem within 48 hrs working day.

If you're willing to try it, open the computer, disconnect the power button's cabling, and reseat it firmly.  Then do a firmware update (if applicable) and BIOS factory reset.

You can get the firmware update from here:

http://www.dell.com/support/drivers/us/en/04/Product/optiplex-3020-desktop

Dell has listed the BIOS update as "recommended."

Your box is still under warranty?? if i am you i wont do anything.. let the vendor handle everything.

Tankgergoblin, the computer has a Dell Pro support and the Unisys tech came out and couldn't figure it out. So they sent a replacement computer. So I did the same thing.. installed all the software in my office.. worked fine.

Then took the replacement computer to the client site (a business building)  AND SAME THING HAPPENED.  2 computers.

epichero22. I don't thin it's the BIOS since it had no problem in my workshop at first. I just happens when it goes to the client's office.

I can't think of why it's happening.   Is there a power issue?  I mean it's in on a surge protector.... And another computer is on the same outlet without a problem. so I don't think it is a power quality issue.

Did you bring back to your site and test it out does it work?

also did you try to plug the power direct to the point without power surge? if not try it.

>>  Then took the replacement computer to the client site   <<   it looks like the problem is in the client site.
but explain a bit more explicit : to power on, you need to hold the both switches ?  or what exactly?
did you try another power cord, and power outlet (another room maybe, for testing) ?

Yes, different power cord, different outlet, different surge protectors were all tried.

I have not taken a malfunctioning computer back to my office to test it again... but at the client site, both buttons have to be pushed for it to power on, on both computers now.

I've been scouring the net to find out what the button on the power supply is. Is it a reset button? I'm not sure. Maybe I'm suppose to hold it down for 10 seconds to reset the Power Supply? I am completely baffled.

post a picture of the button on the PS plse !

This is what it looks like.
From Dell's website.
PSU.jpg

is the switch the red - or blue arrow ?    it could be the reset if the PS cut out for overvoltage, or current
anyhow, I never saw such a switch - it maybe a reset switch; but I also could not find anything on it
to be sure, best ask dell about it -  at least  they should know

Even Dell technicians were stumped... but it all of a sudden started working again.
Now it powers on with the switch just from the front.
Have no clue what happened.

the only explanation i see is that the back switch did not make a contact, so you had to hold it while pushing the start button in front
and now  -by exercising it several times, it does  make contact

I've requested that this question be closed as follows:

Accepted answer: 0 points for TechGoingSolo's comment #a40062116
Assisted answer: 250 points for nobus's comment #a40062336

for the following reason:

The problem just fixed it self on its own. No real explanation.

I have a Dell optiplex 3020 machine with a new power on issue . The system is good , when I plug the power main board power indicator is on . But when i push the power button machine does not run. there is a small button in the back of  the computer in PSU. when I push it computer runs for the pushing time. when I stop pushing machine goes off. what is the problem ?  I have checked the power button/ ram /C-mos etc everything is ok .
.

post your question in your own thread plse -