820-00165 Cycling

[bjf]

This board came in looking very clean. I can't find any significant signs of a spill. It's cycling the CPU. I can't find any shorts anywhere. 3V42, PPBUS 3V3_S5, 5V_S5 are all stable. I attached pre-ultrasonic cleaning pictures. Not sure of a good next step.

 

[2informaticos]

I don't see any reason to use UC there.
Did it change its behaviour after that?

Check all SPI Bus Series Termination resistors and traces/solders around U6100/01.
Try new BIOS also.
Do you get 3V at pins 7 & 3 of U1950?