PC won't start right away.

Hi,

after replacing processor 1600 x to 5600 x and motherboard MSI B350m to ASUS B550m-a, PC won't power up when it was shut down for a few hours.. It will only start after multiple tries and cables disconnection.. etc after about 20 to 30 minutes.. Once it is up and running no issues whatsoever.. Now i leave it on sleep mode..

The new peocessor and motherboard are second hand ones..

We replaced CMOS battery but it did not solve the problem..

Any tips please?

Thank you