Dell OptiPlex 9020 SFF
system won't show screen, power led is white, cpu fan revs, but not loudly.
Dell Support were friendly & helpful but didn't get me anywhere, so it's DIY :-).
Power supply test (button on PSU) runs OK when turned off and PSU led is green, so not a power supply problem.
Shutdown and remove power for 1min - no change.
Disconnect HDD, AMD graphics card & DVD & one (of 2) memory module- no change.
Remove both DIMM, pwr on - system beeps - good motherboard is alive :-)
Disconnect power, remove last Memory DIMM & swap for the other one & system boots into BIOS Menu (as there's no disks to boot from)
Pwr down, connect HDD - Pwr up -no screen, no boot. (After this you're back to a dead PC agian)
Long story short - ONLY if you change the DIMM & leave ONE DIMM by itself THEN will system start, but not if any disks are connected. (if you only have one DIMM use Slot2 which works)
The Fix.
Download Dell & Create Boot Disk - here (you can copy the URL, just delete the spaces)
http:// www. dell.com/support/article/us/en/19/SLN143196/EN
instuctions here
http:// www. dell.com/support/article/us/en/19/SLN284433/en#How_to_update_USB_flash_drive
BIOS file Here
http:// www. dell.com/support/home/us/en/19/Drivers/DriversDetails?driverId=N08H6&fileId=3542449770&osCode=W764&productCode=optiplex-9020-desktop&languageCode=en&categoryId=BI
In BIOS Menu, Disable SecureBoot, Change BIOS BOOT to Legacy
Run BIOS update from USB
Boot from usb & type BIOS package name o9020a16.exe, enter & you'll be updated to latest version
DON'T POWER OFF - the updater will restart by itself!
In BIOS Menu, Change Boot to UEFI, enable SecureBoot (if you don't you can have startup problems)
Connect HDD & other components & you should be good to go!
Bryn