CPU ok; RAM ok; POST beep ok. What could be the problem?

[Eduardo Elle]

So I am working for a grocery and a PC based POS is driving me crazy.

first thing I noticed was there was no display (Working monitor and chord).
LEDs and Fans Turn on - Chassis, CPU and PSU

since we have multiple POS, I started replacing parts from a working POS. (BREADBOARDING)


RAM - Still no display and post beep
CPU - Still no display and post beep
PSU - still no display and post beep
HDD - still no display and post beep

so I thought its a MOBO issue. so I removed the RAM and CPU one by one both caused a POST BEEP.

(Images of breadboarding)

(Images of CPU pins)

I dont have any other clue. HELP Pls.

BTW I attached a keyboard and the NumLock LED is working (which i consider the keyboard is working)

 

[Mark_1970]

So I am working for a grocery and a PC based POS is driving me crazy.

first thing I noticed was there was no display (Working monitor and chord).
LEDs and Fans Turn on - Chassis, CPU and PSU

since we have multiple POS, I started replacing parts from a working POS. (BREADBOARDING)


RAM - Still no display and post beep
CPU - Still no display and post beep
PSU - still no display and post beep
HDD - still no display and post beep

so I thought its a MOBO issue. so I removed the RAM and CPU one by one both caused a POST BEEP.

(Images of breadboarding)

(Images of CPU pins)

I dont have any other clue. HELP Pls.

BTW I attached a keyboard and the NumLock LED is working (which i consider the keyboard is working)

With just cpu/heatsink/ram/keyboard/psu on the board, reset bios using the jumper on board and try