The short answer is: NO
You cannot put faster memory upgrades into an old MacBook. You might be able to add more memory to your MacBook depending on your specific Apple MacBook you’re in the market to upgrade, but no – you cannot add faster ram. Adding more RAM, yes you can – assuming you have not maxed out the MacBook RAM already on your Apple MacBook.
MacBook Memory comes in two flavors currently: DDR2 PC5300 sdram sodimms, and DDR3 SDRAM sodimms running at 1066MHz, which if you notice, is twice as fast as the older MacBook ram. For the older MacBook models, the maximum memory you can apply again depends on both who you talk to and what exact older MacBook you have. Some memory stores like OWC, will state that on the MacBook models where 2GB is the maximum RAM you can squeek another 1GB of RAM into the old MacBook by installing a 1GB memory upgrade for MacBook in the first slot and a 2GB memory upgrade module in the second slot. It’s always to suggest what Apple suggests, and leave the overclocking and other performance tweaks to others. If you are insterested in squeezing every last drop of performance out of your Apple computer accelerate your mac is a great resource about speeding up your MacBook
The same goes for the slightly newer MacBooks that maxed out at 4GB PC5300 DDR2 sdram sodimms : word on the street is you could effectively install 6GB of RAM into these older MacBooks, and it’s been reported to work just fine, but I can’t recommend doing this, if Apple states that 4GB is the maximum MacBook RAM, then that’s what I state and list as the MacBook maximum ram limit.
By theory, you should be OK with more RAM than officially stated, due in part that when the older MacBooks were released, the larger memory sizes were not released yet so the maximum memory stated was in part due to the biggest RAM upgrade available for MacBook at the time. But still, I list what Apple states as the maximum memory allowable.
**Cheapest MacBook RAM Prices.
Below is a little chart with the lowest ram prices for both older discontinued MacBooks and new and current shipping MacBooks too: