What's the Best PC Upgrade You've Ever Made?

Every PC builder has that one upgrade that made a huge difference.

Mine would probably be upgrading from an HDD to an SSD—it completely changed the experience.

What about you?

• Better GPU?
• More RAM?
• Faster SSD?
• Better cooling?
• New CPU?
• Something else?

Share your best upgrade and tell us why it was worth it. Your answer might help someone planning their next build!