I recently inherited an unused PC from work. It's an Optiplex 780 with a faulty power supply.
I replaced the power supply with a working one from an old Optiplex 740 and also had to buy an standard ATX 24 pin to mini ATX 24 pin cable in order to use the 740' PSU in my Optiplex 780.
I have plugged in the power cord (but no mouse & keyboard because I don't have any USB keyboard available) and I expected the computer to show DELL logo as well as on screen POST messages during power up but instead I can see the following :
1) Power button in orange color. No blinking. : according to service manual it means PSU is probably OK and PC has reach booting stage 2.
2) 1,2 & 4 green diagnostic lights are on. This combination (1,2,4) is not listed in service manual so I have no idea on the possible kind of error.
Any suggestions about the possible error and how to fix it?
"...Never in the field of human conflict, was so much owed by so many to so few..."
[ Winston Churchill, about the RAF pilots during WW2 ]
Hello! I would unplug everything go into the computer and unplug any cards you have like graphics card and network cards etc. Also unplug your HDD and Optical Drives and plug them all back in and see if that clears it. I looked at the manuals you did and just combined 1,2 and just 4.
If I hazard a guess, I'd say it's the video card based on code 1,2,4.
1,2 = A possible expansion card failure has occurred.
2,4 = A possible graphics card failure has occurred.
I suspect you may be seeing a combo of both of those LED codes. So first thing is to reseat the video card in its slot.
And if this PC sat around for a long time, unplugged, with a defective PSU, then you probably want to replace the motherboard battery right away, if nothing else than to rule it out as contributing to the problem. It's a CR2032 3-volt lithium ion battery, ~$2 at discount stores.
Forum Member since 2004
I'm not a Dell employee
Duracell DL2032 also works. They keep them in the *** section of grocery stores because blood sugar meters use the same batteries. Even though they say medcal device they work on computers just fine.