OK guys, first post here I know... but hopefully one of you guys can help me out. I have a mid 2010 unibody MBP that came stock 4gb of RAM and I wanted to update it. Went to Best Buy and purchased 8gb of PNY brand RAM. Came back to the office and installed. This is what happened: -(with both 4gb cards in) froze up at the apple with even the spinwheel freezing. -(with 1 2gb card and 1 4gb card) works fine. even reads that it has 6gb of ram. -(switch the 4gb card and 2gb card) again works fine, reads 6gb of ram. Why will the cards work separate with an original card, but not together? Anyone have this happen before? What should I do? Let me know any info that could help out, PLEASE AND THANK YOU!