Max out a ThinkPad T420

The T420 is a favourite because you can open it with a few screws and upgrade almost everything. A cheap old one can feel fast again for not much money. Here is where to spend. Memory first. The T420 takes two RAM sticks. RAM is the short-term memory the laptop uses to juggle open programs. More RAM means more tabs and apps at once without slowing down. Most people fit 16 gigabytes total, two 8 gigabyte sticks. Search for T420 8GB DDR3 SO-DIMM and buy a matching pair. Storage next, and this is the big one. Swap the old spinning hard drive for an SSD. An SSD is flash storage with no moving parts, so the laptop boots in seconds instead of a minute. Any normal 2.5 inch SATA SSD fits. This one change makes the machine feel new. Now the screen. The T420 shipped with a dim, washed-out display. You can swap in an IPS panel, which has richer colour and wider viewing angles. This mod is popular but fiddly. Some IPS swaps need an extra adapter cable or board to work with the T420, and the exact parts change over time. Search for T420 IPS mod and read a current guide before buying, because people disagree on the cleanest way to do it. A note on the keyboard. The T420 has the beloved classic ThinkPad keyboard with seven rows. Many owners rate it the best laptop keyboard ever made. If yours is worn, replacements are easy to find and swap. Some people even mod a T420 keyboard into newer ThinkPads because they miss it that much. You can also lift the processor a step within what the board supports, but RAM and an SSD give you the biggest jump for the least effort. Check this ThinkPad's spec sheet in the library for its limits.