MacBook Pro Crashes Randomly

Hi Everyone,

I have a Macbook Pro 15-inch Late 2011, 2.2ghz i7 quad core, 8gb RAM

Yosemite 10.10.2

I recently ran into a problem where I can barely use my MacbookPro because it crashes pretty frequently now. A black bar comes through the screen and the computer freezes and does a hard reset with no notices. On two occassions when the computer finally reset itself the startup sound keep looping until I held down the power button to shut it down. Last night I did an extended AHT test and the computer actually did the same freeze doing the memory test.

Do you think this is a Main Board issue or should I be able to replace the RAM and should fix the issue?

I have attached images of the issue.