Asus ROG Strix B450-F Gaming II stuck on POST

[Twiesel]

Hey y'all,

I am currently working on an Asus ROG B450-F Gaming II ATX Mainboard. The board is in very good condition (no missing components/scratches), but when I power it on using a Ryzen 3 1200 and one stick of DDR4, it gets stuck at 1,4A with none of the POST-LEDs lighting up.

I checked all voltages, which are present. The CPU gets slightly warm.

What I did try:
-Resetting CMOS
-Reflashing BIOS (manually and using the flashback tool)
-"cleaning" the socket with isopropyl alcohol
-using several sticks of DDR4 in every slot

The PCH-Resistance looks good (around 30 Ohms iirc). Nothing gets particulary hot.

I am a bit at a loss here, as I have not much experience with AM4. I dont know why the board does not POST and which signal is missing. I got every tool available I guess (oscilloscope, soldering station, hot air...).

My next step would be opening up the socket, but I know that I will probably screw up and break one of the locks... The attachement is the boardview of the Gaming I version, I couldnt find the one of the Gaming II.

It would be awesome if I can get some input on how to move forward. Thank you in advance!

Link to boardview - https://www.badcaps.net/forum/troubl...-01a-boardview

[noname2024]

Cannot boot up and power is on (FF/00)
check Net Type Net Name States
CPU Power VCORE 0.75~1.5V
CPU Power VDDSOC 0.75~1.2V
CPU Power VDDP 0.9~1.05V
CPU Power +1.8V 1.8V
CPU/MEM Power VDDQ 1.2V
MEM Power VTT_DDR 0.6V
MEM Power VPP_DDR 2.5V
SB Power +1.05V 1.05V
SB Power +2.5V 2.5V
Sequence Signal O_APU_PWRGD 3.3V
Sequence Signal S_PLTRST# 3.3V
CLK Signal S_CK_100M_HUBP 100MHz
CLK Signal S_CK_100M_HUBN 100MHz
CLK Signal S_CK_100M_M.2P 100MHz
CLK Signal S_CK_100M_M.2N 100MHz
CLK Signal S_CK_100M_X16SL1P 100MHz
CLK Signal S_CK_100M_X16SL1N 100MHz
CLK Signal S_X48M_X2 48MHZ
CLK Signal S_X48M_X1_R 48MHz
CLK Signal S_CK_33M_LPC_R 33MHz

[Twiesel]

Thank you for your answer. I went ahead and checked every voltage you have listed and indeed, S_PLTRST# is low. The other voltages are fine, exept that 1.05V is at 1.03V, but I guess that should not matter (?). Any idea on how I can continue? Do you know what S_PLTRST# is supposed to do?

[Twiesel]

I checked the signals again and it does seem like O_APU_PWRGD# is missing. Its hard to find as the schematic of the Gaming I version is a bit different then the one of the Gaming II. But There is one resistor next to the socket, which also exists on the Gaming II, carrying no current. It is not being pulled down though. I assume that O_APU_PWRGD enables the chipset, which barely gets warm in the current state.

What could lead to the CPU not outputting a PWRGD#-signal? I am certain that all voltage rails are running...