Dell Optiplex 780 Won't Complete Power Up

Dell Optiplex 780, Ultra Slim Desktop case. Refurb purchased from NewEgg last November. Son added a graphics card this spring. Worked a while, then he had power up problems. I pulled the hard drive and scanned it while connected to another computer as an external drive, expecting to find a virus. WebRoot had expired, did not bother to let me know. No virus found. Reinstalled the drive. No success at first. Later, he had it working. He cannot tell me exactly what he did. I had him pulling and reinstalling memory, drive cables, etc. to check for bad connections. Now, after working for a day, it will not power up. Got a copy of the Dell service manual. The pc has passed the power supply tests. We found a helpful video.

Power light: solid amber
Diagnostic lights: 2, 3, 4 are on

This is listed in the Dell service manual as a possible USB failure. No peripherals are connected (not even the keyboard). If a USB port craps out, will is stop the pc from booting?

 

Graphics card is XFX One (2GB), Deluxe Edition, PCI-Express.
Model: ON-XFX1-DL
Part no: ON-XFX-DLX2, Ver 4.E

Installed it in March of this year. Had some issues with drivers and BIOS, but got that worked out and my son used the pc for a couple of months afterward without issue. Now we have this power up problem. Even when the graphics card is pulled out, same issue.

 

How many watts is your current PSU? According to specs, the max you could currently have with an OEM supply is 300VA @ 65% PF (265W).

XFX recommends a bare minimum of 400W, preferably 450W.

 

Is this what your model's case looks like?

http://www.dell.com/support/article/us/en/04/SLN289307

Or is it a mini tower?

 

The case is SFF, power supply is 235W. I was not previously aware of the disparity in power supply requirements. And yet, the graphics card worked in the past. Now, even with the graphics card removed, power up/boot up is not successful.

 

When you purchased the Optiplex, did that XFX 1 card come with it or did you purchase it separately and install it. If it came that way from NewEgg, they should have known about the PSU requirements.

 

Purchased separately. Bought the pc in November of 2015, then my son bought the graphics card I believe in March of this year.

 

Pull the power cord and hit the power button, then apply power and hit the button, anything?
Did you pull *everything* and leave it out while trying to start? Pull cards, USB devices, RAM, case fans, just leave the power, mobo, and CPU, then power it up?
Some cases they use the USB bus internally, so it could be on the board, not a device you've plugged in.

 

We will try this procedure this evening and post results.

 

With a light card like that, the stock PSU could push it for a little while. However, it can't be overtaxed forever.

Though you have the voltage to push a few LEDs on a PSU tester, that doesn't mean you have the amperage to drive components.