the title is my quistion & do i need to update the bios or will the motherboard comes ready for the cpu?
im talking about the i5 9400f btw
im asking cause when i do system build it does show compatibility issue with the motherboard
Depends on what BIOS version the board has.
If you already have a B360 mobo, you'll need to update BIOS using an existing compatible CPU in order to support the 9400F
If you don't have a mobo and are purchasing one with the CPU, take a newer B365 mobo (no update required). https://pcpartpicker.com/products/motherboard/#c=136&sort=price&page=1
p.s. just a quick heads-up (although im sure you're already aware), the 9400F doesn't support integrated graphics and will need a discrete GPU.
i didnt even know about the B365 chipset until you said that.