I recently got a new gpu, an EVGA GeForce 750 ti sc. Ever since then, my ram hasn't been working quite right. Sometime when i check it, it will say 15/16 gb usable. So I switched to 2 sticks of 1 and 2 sticks of 4. It then said 10 gb of ram. All available. I then removed the 2 sticks of 1 and it went back to taking some away. It now says 8 gb ram (3.98 available.) What is the problem? The gpu minimum wattage is 400w and my power supply is exactly that max. Is that the problem?