Upgrading the RAM (Random Access Memory) can improve a computer's performance, especially when running multiple programs simultaneously, because it increases the amount of information that can be held in fast-access memory. More RAM allows for more processes to be run smoothly without having to swap data to and from slower storage solutions, like hard drives or SSDs. The CPU wouldn't necessarily directly increase multitasking capabilities, and the GPU mainly enhances graphic processing. A cooling system improves heat dissipation but does not impact the amount of data that can be actively processed.