I would ask why would you want to do such a thing first?
I would guess at some hardware/software issue that needs a cold boot but as per the following article which also answers your question -
http://www.windowsitpro.com/article/windows8/force-full-shutdown-windows-8-closing-kernel-session-140921
"Windows 8 starts so fast normally is because it doesn’t shut down the kernel session, which contains the system state and takes most of the time to start to initialize during system boot. Instead, the kernel session is actually hibernated...
This does mean that between boots, the system isn’t re-initialized (because it’s not typically needed). If you do make a hardware or system change that requires a system initialization, the system typically handles this for you automatically. "
to actually perform a full shutdown and cold boot:
open the command prompt
run the following command: shutdown /s /full /t 0
the /full flag performs a full shutdown instead of only hibernating the kernel
its worth pointing out that Win 8 shutdown is not really hibernation as it will shutdown all your applications, it only hibernates the core kernel to improve boot speeds