Question 2.9 GB free of 8 GB on 64 bit?

Check your CPU temps. I like using HWInfo64 because I can see a lot of what's going on with my hardware.

You have to make sure all your background tasks are closed. Just using Firefox with multiple tabs across 2-3 instances on multiple monitors, plus MS Word and maybe notepad and calculator and maybe another lite program, I can easily use up 8GB system RAM. A lot of the new games from last year also use more than 8GB. 16GB is becoming the minimum for gamers.