zeronltu :
I wan't to buy a new monitor. (144hz). My pc is
╠♦ CPU : Intel Core i3 6320 @ 3.90GHz
╠♦ GPU : GeForce GTX 970 4GB
╠♦ HDD : 1TB
╠♦ RAM : 8GB
My pc can run 144hz monitor, ir better change CPU
Depends on what/how you want to play.
If you're asking for 144hz @ max/ultra on the latest titles then, no you need much more powerful GPU+CPU for that.
If you're looking at older/lighter titles @1080p and are willing to fiddle with the game's settings/config then there are certainly situation where the 144hz screen will be of use to you, especially since a monitor, rather than a CPU, will stay with you through multiple builds.