After following the advice given above, let's look at your RAM.
Your crashes can be caused by several things adding up, the above advice will help to narrow them down.
First, can you post your System Specs?
Use these links to find your system specs. Speccy Free System information Utility D/L CPUZ
and post a snip of the CPU, Mainboard, Memory, and SPD tabs.
For posting the information , enter 'Snipping tool' in the Start button > Search box, hit enter. Select the area you want to post and save to a convenient place. How to Post a Screenshot in Seven Forums
Have you been checking your temperatures? Use Core Temp
, to check the CPU temps when at idle, under load and/or testing.
Let us know the minimum and maximum temps you get.
Go to your BIOS and tell us what the CPU, RAM and the CPU integrated memory controller voltages are, these are important, need them to adjust the RAM settings.