Having a ram issue with my Mac Pro 3,1 (Early 2008). Have 4 4GB sticks of 800 MHz DDR2 FB-DIMM installed. Everything works fine for about 5 minutes, then the computer crashes and restarts. After restarting the machine is reading 2 4GB sticks of ram and 2 2GB sticks of ram. I have bought new ram and risers thinking this would resolve the issue but still no luck. Any ideas?