MacBook RAM and External Monitor question...

So a few days ago I posted how hooking up an external monitor to my C2D MacBook made my MacBook screen go a little crazy, forcing me to bring it in to my nearest Apple Store. The guy there told me that it had fried the Logic Board and that it would be replaced (under warranty). However when I go to pick it up today the repair report said that they simply just took out the 3rd party RAM that I was using, saying that it caused the problem. I can't complain because now my MacBook runs fine. The thing is that I have had that RAM in for over 3 months without any problems. I now have the original two 512 MB sticks that came with my MacBook and do not plan on using the 3rd party ram again. Would it be safe to attempt to plug in the external monitor again, considering I have the original RAM and the external monitor simply just caused a flaw in the 3rd party RAM? In other words, can the external monitor cause a fault in just the 3rd party RAM and not my logic board?