[SOLVED] ASUS Prime B450M-A motherboard or ASUS Prime B450-PLUS not turning on

[s1mon111]

Hello,
I have a problem with starting a new computer based on the ASUS Prime B450M-A motherboard or ASUS Prime B450-PLUS

Motherboard: ASUS PRIME B450-PLUS / ASUS PRIME B450A-M
CPU: AMD ATHLON 240GE
RAM: GOODRAM DDR4 4GB
PSU: AEROCOOL AEROCOOL PGS VX-800plus 800W

I plugged 24-pin EATXPWR and 8-pin EATX12V, attached CPU and RAM, when I'm turning on my PSU some diodes on MoBo are lighting but for example fan in PSU is still off (it should be on I belive). The fan on the CPU is also not spinning. The speaker is also silent. Rather unlikely that both of these boards are damaged.
Any ideas?

 

[rgd1101]

cpu fan should spin.
test with different ram slot for the ram?
check for bend pin on the cpu?

 

[s1mon111]

I tried each RAM slot, no bend, checked also.

 

[drea.drechsler]

What BIOS version are the boards on?

Many of the B450 board mfr's dropped BIOS support for earlier CPU's and APU's when Ryzen 3000 came out. So those APU's may work only on very early versions...like before Ryzen 3000 was released.

Conversely, if you've a later model of the APU it may not work if the BIOS is too early, as in prior to 0804 on the PRIME B450-Plus for instance.