Q: RAM induced kernel panics

So I upgraded the RAM from 4GB to 8GB on my 27" mid 2010 Mac and It keeps forcing me to power off (gray screen appears).  Could this be a problem with the RAM or with the comuter itself?  Im using the recomended RAM for my iMac, PC3-10666 SoDIMM.  I traded out the two original RAM modules (2x2GB) for 2 4GB modules.  I purchased the RAM from best buy, its PNY brand if that makes any difference.