Originally posted by Toke
What motherboard do you have now? I'd imagine a 970 Or a 990fx
OP has a Gigabyte GA-78LMT-USB3.
@OP; It shouldn't be your motherboard that's preventing you from running a 64-bit OS. The only thing that has control over whether you can/cannot install 32-bit/64-bit version of Windows is the CPU.
The OS doesn't choose which bit it runs at. You're running a 32-bit version of Windows 10 because you installed the 32-bit version. Did you try installing the 64-bit version?