Atomic Rooster
Omnipotent One
- Messages
- 11,161
- Location
- USA
You can mix speeds, but they will both run at the slowest stick's speed. So if you do mix speeds, make sure the new one is faster then the old one. You don't really have to worry much about brands. The motherboard supports up to DDR333, but you can use DDR400 as it's backwards compatible with the lower speeds.