Moving Gateway harddrive to HP PC

Okay, so I am moving my hard drive from my old gateway PC to my HP PC. It detects that the hard drive is plugged in, it just wont boot it, even from the boot menu. Any Ideas?

If the o/s was installed on another pc drivers etc will not be the same and disk setting may not be the same so it wont work and it wont activate either

Its probably because one computer was legacy Bios (and matching MBR disk), and the other computer is UEFI (and matching GPT type disk). Since, more than likely, the old computer was legacy Bios, you can try entering the new computer UEFI setup and enabling legacy BIOS or CSM booting mode. Also disable secure boot.

Also if the old computer was set to IDE SATA controller type and the new computer is set to AHCI SATA controller type, that will keep Winodws from booing as well.

As far as new hardware and drivers - Windows 10 does a very good job of picking up the new hardware and installing drivers for the new hardware, so there isn't much worry there (other than MBR v. GPT disk type and IDE v. AHCI SATA controller).

If the new computer already had the same version and edition of Windows 10 on it once, then the Windows 10 on the hard drive being moved will self activate based upon the digital license for the new computer stored on MS Activation Servers.

NavyLCDR said:

Its probably because one computer was legacy Bios (and matching MBR disk), and the other computer is UEFI (and matching GPT type disk). Since, more than likely, the old computer was legacy Bios, you can try entering the new computer UEFI setup and enabling legacy BIOS or CSM booting mode. Also disable secure boot.
Also if the old computer was set to IDE SATA controller type and the new computer is set to AHCI SATA controller type, that will keep Winodws from booing as well.

As far as new hardware and drivers - Windows 10 does a very good job of picking up the new hardware and installing drivers for the new hardware, so there isn't much worry there (other than MBR v. GPT disk type and IDE v. AHCI SATA controller).

If the new computer already had the same version and edition of Windows 10 on it once, then the Windows 10 on the hard drive being moved will self activate based upon the digital license for the new computer stored on MS Activation Servers.

I'm not that good with the bios. The old PC was running windows 8 and the gateway is very old, so how do I do what you said? "you can try entering the new computer UEFI setup and enabling legacy BIOS or CSM booting mode. Also disable secure boot."

To get into UEFI setup, you have to press the proper hotkey immediately after power on, when the HP logo screen is still up before you get to any Windows screens. On an HP, it is probably going to be ESC. It could be DEL, or one of the F keys as well. Need to look in the manual for your computer to see what the UEFI setup key is.