well so far, heat = give your computer a good clean
works wonders .... (you can buy compressed air online, or carefully with a hoover and paintbrush slowy brush all the crap out and hoover it up as its floating about).
Dual monitors you can already achieve with your current setup, and for 144hz monitors, its worth considering the following technologies
G-sync (Nvidia & propitiatory costs extra)
Open Sync (AMD & is open source so much cheaper) you can also already utilise this with your current hardware.
have a read here
http://www.digitaltrends.com/computing/nvidia-g-sync-or-amd-freesync-pick-a-side-and-stick-with-it/
hopefully this leads you slightly better informed rather than more confused.