Cutting to the chase bought a used MacBook with 2gb and it boots up no problem .also bought new ram 4 gb (2x2gb) installed it next day. When I boot it gets Stuck at Apple logo the swirly thingy below it freezes. I have googled for a solution and saw that I should try and pram reset ( cmd + option +p+r) booted right up checked system information showed up as 4gb 667mhz. Restarted the computer to see if it really fixed the problem. Restarted no problem. But once I shut down completely and start back up I'm back at square one. I don't know what else to do. Hopefully those of you with older MacBooks can chime in. Much appreciated for the help!