I have a G73SW-BST6 and mine does the same thing. If anything is plugged in to the USB 3.0 it freezes at the boot screen. I've been looking into it but no luck. Maybe its a BIOS problem, I really dont know.
I upgraded to 16GB with the Hyperx PNP on my G73Sw and it has 2 slots under the panel and two under the keyboard. To get to the slots under the keyboard you have to disassemble it to get to them. Be careful when removing the keyboard because its atta...