Weird problem with my PC(boot only in horizontal position)

[MSK2002]

Hi guys , i have an HP 6300 MT and I'm having a weird problem the PC boots and works only in Horizontal Position if i try to put it back vertically while it's running , it freezes instantly and won't boot back unless i put back horizontally, now i had this issue way back and i kept using the PC in horizontal position until one day i put back vertically and it works without changing anything  but today this issue is back and i want to fix it permanently and i hope you can help me.

My specs :

I5 3470 , 16Gb ram, Palit GTX 1050 Ti ,320W PSU, Windows 10 Pro 64Bit

Big thanks in advance.

[Prométhée]

Hello
you say this happens when the pc is on !?
You should only do this if the computer is turned off, if it is shaken while it is running, it is not highly recommended.
Now do you still have the problem if the computer is turned off and then restarted after change?

You have to open the computer, and check if there is not an element that could move and cause a malfunction
check if everything is well fixed, if a cable does not block a fan for example etc!

[MSK2002]

Yes my PC doesn't boot in vertical position even the bios doesn't shows up , i checked everything nothing is loose but i didn't checked the CPU and it's socket.