Technical Support dell Optiplex 780 2 3 4 blinking

[ABEBE]

I face dell optiplex 780 with 2 3 4 green light blinking with power button fixed led light , I tried to reprogram the BIOS , no help , the CPU IS HOT all voltages are working but it shows 2 3 4 blinking , when I search on Dell support it says the problem is related to USB , If any help appreciate

 

[Hosein Asadolahi]

I face dell optiplex 780 with 2 3 4 green light blinking with power button fixed led light , I tried to reprogram the BIOS , no help , the CPU IS HOT all voltages are working but it shows 2 3 4 blinking , when I search on Dell support it says the problem is related to USB , If any help appreciate

disconnect all components from motherboard and test it .
try with new adaptor and test .
replay result plz .

 

[ABEBE]

appreciate your response, I am testing on the table with no connection other devices ( HDD ,CD )
I checked on working power supply , but the same.