sorry, I have the PG348Q. Its 100hz but very expensive. PG248Q looks great, but is 24"/1080p enough? I bet you can find a a 27" 2k at 144hz for under 500
because you have Nvidia, definitely look for something with G-sync. Lots of hz are great, but in combination with G-sync will make a world of difference for gaming. G-sync monitors are pretty expansive.... try to look for a deal!
If you are having so much issues with the motherboard, I would just exchange it with a type or brand. I don't think the power is the issue....600W is more than enough unless its dying on you.
For that price, the crappy 60hz monitor killed it for me. all that power & limited to play at 60fps. Samsung 21:9 monitors are terrible. They should have use Asus or Acer 34" @100hz