Last week I installed my Sapphire Radeon R9 270x Overclocked and an EVGA 550GS power supply. Before, I had Intel's integrated graphics which didn't give me enough power to run many newer games. I'm pretty sure I've installed everything correctly but when I turn on my pc with the hdmi cable in the gpu and everything in the mobo the screen gets no signal but I can hear the pc turning on. The pc works normally when I put everything in the mobo. Any help?