Try it with just one of the ram sticks connected, try both of the sticks individually just to see if one of them may be faulty, if your still not getting a display, try connecting your monitor straight to your mobo & using the onboard GPU instead of your graphics card. Once you've turned the PC on & if you get a display and the usb doesn't load, see if you can access the boot options using F2 instead and selecting "Boot from USB".