Installing a 3rd stick of RAM causes a reboot loop

[tankimakura]

Recently I purchased another G.Skill Ripjaws 2x4gb kit (1333hz). I know that it is not faulty because it works when I run the computer on the new kit. I have even mixed and matched the two kits and they still work.
So far I have:
- Cleared the CMOS
- Replaced the BIOS battery
- Updated the BIOS
- Unplugged my graphics card

How do I get my computer to run all 4 sticks without my computer restarting itself?

SPECS

Gigabyte GA Z68P-DS3 (rev 2)
GTX 770
Antec 520w power supply
G.skill Ripjaws 2x4gb (1333hz)

 

[Calvin7]

Memory manufacturers only guarantee memory in the form it is sold in.

Workarounds to get extra memory to work include:
Lower memory frequency
Relax DRAM timings
Increase DRAM voltage
Lower CPU multiplier