Hi,

I am sorry to write in enemy language - I am from Bulgaria.

I have a problem board ASRock X470 Master SLI that does not start at all.
Power Button - no reaction from the board.
3VSB and 3VSB_A and 5VDUAL are present in S5 state.

Short on 12V, 5V and 3V are not found on the ATX connector.

3.5V are present on the power button.

I short ATX pin 15 and 16 and the board starts - no beep, no video. BIOS chip has been changed and flashed with BIOS from the same board.
When board starts 12V are present on the CPU FET Drains (SM4337NSKPC)

Can you please give me some inside here? I am new to motherboard troubleshooting but eager to learn.
The boardview file is attached for reference.

what is the voltage on pl24?

PL24 - Pin1 (1V8 PHASE) - 1,66v - 1,70v
PL24 - Pin2 (+1.8VSB) - 1,80v

PU18 - Pin5 - measured on :
RP328 Pin2 - 2,5v
RP324 Pin1 - 2,5v
DP6 Pin1 - 2,5V
DP6 Pin2 - 3,2V

PU18 - Pin8 - Measure on :
RP330 Pin1 - 5v
CP464 Pin1 5v

So, do you think PL24 should be changed, as the output V is lower then 1.8v? Resistance of PL24 on the board is 1.2ohm.

No, in this case everything is fine. sometimes the pu18 fails and then the output is 5 volts. it would be bad, but now everything is fine.

Ok, so PCH is bad or I can check something else?