I have a bootable USB stick for Windows 7 Professional x64 that contains an EFI boatloader (I think).
It's always installed 64-bit just fine but I tried using it on an older HP machine and it would only install 32-bit Windows.
I don't get any option to choose 32/64-bit during installation and always thought that it was only a 64-bit iso.
The only way I could get the ISO to install as 64-bit was to burn it to an ISO instead and to use that.
Why on this computer did it fail? The processor is 64-bit compatible.