Open your laptop and look at your drive. Last time I saw this it was the drive that was almost disconnected from the connectors. The stupid laptop had a drive enclosure so big that the drive was almost loose in that enclosure moving around. I was shocked that nothing was screwed down or it was missing a part behind the HDD that makes it not move at all.
Not saying it's not the RAM but it could be something else that was caused by the removal of the onboard + adding the new RAM that caused another issue.