When I used to teach high school, I would describe RAM (Random Access Memory or simply “memory”) as physical desk space, and virtual memory as putting stuff on the floor. So, stuff on your desk (RAM) is the stuff you can access right away, and when the desk is full, you have to put your stuff on the floor (the hard drive) which takes longer to get. Since all hard drives are slower than RAM, it’s always good to have plenty of RAM.
Over the years I have found it is pretty rare to find memory defects, but when they do exist, your system can become incredibly erratic. Having faulty RAM can cause your system to give you BSODs, lock up inexplicably with no warnings or error prompts, restart endlessly in a loop, not boot at all and can even cause a loss of data if you are able to run the system and a piece of software is attempting to access the faulty area(s) of RAM. I am not necessarily suggesting you purchase ECC (Error-Correcting Code) RAM, but I am suggesting that you take the time to test your RAM at least once — and test it the right way.