RAM is a high-speed memory workspace that the system uses for running programs, loading operating system components, and performing most of its computing tasks.
If you use programs that take up a lot of RAM, you may see the system slow down while the system makes use of the slow hard drive to manage memory contents, to the point where it may sometimes crawl to a near standstill while tasks are running.
As a result, having ample RAM is great for system performance, so I always recommend to go with as much RAM as you can afford to put in your system. Even if you don't need it now, increasing the amount of RAM in your system will prepare your system for when it eventually will be used. These days 4GB of RAM is a standard configuration, but soon that will jump to 8GB or higher as programs and operating systems get more complex.
Because of the increasing requirement for larger RAM capacities, it may help to know exactly how much RAM you can put in your system. These days all of Apple's Macs are 64-bit machines, which means that theoretically they can access terabytes upon terabytes of memory; however, despite this there is a physical hardware limit on the amount of RAM a system can contain. This is true both in terms of physical capability but also in a built-in limit in the system's memory controllers on how much RAM it can recognize. As a result, despite having 64-bit capability, many systems are built with limitations that allow them to hold a maximum of 4 or 8GB of RAM.
Even though they are 64-bit capable, Apple's MacBook Pro systems have been offered with 8GB RAM as the maximum configuration. More recent models, including those released in 2011, have been built with a higher RAM limit, so even though Apple only offers 8GB RAM and mentions this as the maximum amount of RAM the systems can hold, in reality they can recognize up to 16GB if you add it.
These systems are the ones with the model number series of MacBookPro8,x or later, which include the following:
- MacBook Pro 13-inch 2.3GHz dual-core Intel Core i5
- MacBook Pro 13-inch 2.4GHz dual-core Intel Core i5
- MacBook Pro 13-inch 2.7GHz dual-core Intel Core i7
- MacBook Pro 13-inch 2.8GHz dual-core Intel Core i7
- MacBook Pro 15-inch 2.0GHz quad-core Intel Core i7
- MacBook Pro 15-inch 2.2GHz quad-core Intel Core i7
- MacBook Pro 15-inch 2.3GHz quad-core Intel Core i7
- MacBook Pro 15-inch 2.4GHz quad-core Intel Core i7
- MacBook Pro 15-inch 2.5GHz quad-core Intel Core i7
- MacBook Pro 17-inch 2.2GHz quad-core Intel Core i7
- MacBook Pro 17-inch 2.3GHz quad-core Intel Core i7
- MacBook Pro 17-inch 2.4GHz quad-core Intel Core i7
- MacBook Pro 17-inch 2.5GHz quad-core Intel Core i7
While this upgrade is possible, do keep in mind that it will not be cheap. Even though memory prices are very low these days because low PC demand has resulted in a surplus of components, the low prices are only for relatively common RAM modules, which include the 4GB and 8GB upgrades (two pairs of 2GB or 4GB modules, respectively). The 16GB upgrades are not as common for laptop systems, so expect to pay around $600 if you want 16GB of RAM in a laptop system.