Monitor and keybord wont detect unless i reboot arfter first boot

I recently brought a new pc and im haveing a problem with my screen and keybord not been dectected on first start it just stays black screen also my keybord wont light up i have tryed unpluging my hdmi cable and re plugging i have also changed the cable compleatly to a new cable still same problem happens unless i restart my pc arfter it firsts boots i cant see or type anything onley thing that seems to get power is my mouse dock all outher extrnal things comeing out back like my hdmi and keybord dont work unless im to restart then thay both power up like normal and pc runs fine all day long all my outher stuff is getting power due to i use it all day playing diablo 3 online so there is nothing major rong at all maby just something i dont have set right due to it been brand new and all everthing works 110% fine arfter my restart but not on first boot can someone here please point me in the right direction to fixing my problam any help will be grate thank you.

Try booting without the mouse dock connected.
Try booting without any external devices connected (except keyboard).
Let us know the results.