Thinking about building a new system for gaming… other than a monitor/keyboard/mouse, am I missing anything important? (will update later with actual parts I am considering)

• Motherboard
• Hard drive
• CPU
• Video card
• Memory
• Case
• CPU HSF

Seems like there is something I’m missing, but I’m not sure.

Just thought of a couple more things:

• Keyboard
• DVD drive (or probably a Blu-Ray drive for one of my systems)