You may have started off with too much on your plate at once. Try starting with one stick and then check your BIOS settings, making sure to verify that you memory voltage is set to manual and that you have set the voltage to the correct amount. Save and exit. Also, with the amount of memory you're using, you may consider adjusting the voltage up slightly for both the memory and the front side bus (FSB). This will help stabilize the memory controller. Once you've done this, go ahead and install the second stick from that first set. If it boots and is stable, insert the second pair. If you can boot at this point, you can run MemTest86+. I normally tell people to start using MemTest at the first stick, but I think you could probably figure it out if something goes wrong. Make sure you check your mobo manual for the proper slot order.