I have a MSi GE70, and I think the screen can display 60FPS max, then 60Hz. But I would like to buy a 24' 144Hz, and I was wondering if I plug it with HDMI or DVI, the external monitor can display the 144Hz, or the laptop will limit 60Hz ?
Your laptop is not limited to 60hz, your laptop's screen might be, but as long as your laptop can correctly connect to the monitor in question you should be fine...
My own 120hz monitor requires me to use dual-link DVI cable to display full 120hz (and 120fps) - I'm 90% sure that HDMI cannot send more than a 60hz signal so that wouldn't work for you.
Hope this helps a bit!
If you connect monitor using DVI cable, i think it can go up to 144hz. For HDMI, maximum is 120hz.