Bought 4x4gb sticks of ram a few months ago and since my computer has been restarting randomly, without any noise or warning. Today i took out each sticks and tested every slot one by one and every sticks as well separately. They all worked perfectly, but when I put all four together, restarts again, one solution i found was to underclock the ram when 4 sticks are present.
4x Patriot psd34g13332 4gb 1333 mhz
GA GTX 560 OC
Intel I5 3750k
OCZ Agility 4 120gb- OS drive
Seagate 1tb 3.5 7200rpm 64m cache
WD black 750gb 2.5 7200rpm 64m cache
LG blu ray
Windows 7 Home Premium 64bit genuine
some boards are picky with timings. my current mobo wont let me run the ram at 1600mhz until i find the exact right timings which i didnt want to take the time to do. so im just running it at 1333mhz.
you could have something else going wrong too. possibly your northbridge is overheating, ive only ran into this problem with older nvidia chipsets. but its still possible.