Stick with DDR3 unless you're building a whole new PC.

If your motherboard supports DDR3, just buy another 8GB stick. It’s cheap, it works, and 16GB is genuinely useful for everyday multitasking. Going to DDR4 means buying a new motherboard and likely a new CPU—that’s a full rebuild, not an upgrade.

The performance gap between DDR3 and DDR4 on older platforms is small. You won’t notice it in most games or office work. The only real reason to switch is if your current CPU is bottlenecking you and you’re already planning a new build. Otherwise, spend the $20–25 on more DDR3 and call it a day.

Future proofing with DDR4 doesn’t make sense when your current hardware is already on a dead socket. Keep things running until you’re ready to do a proper platform swap.