I'm going to get a monitor for my new gaming PC, should I get a 4K monitor or 1080p monitor

[Matronisaacs]

The specs of my PC is

GTX 1080 GPU
I7 7700k CPU
16GB RAM

If my computer can't handle 4K, can I lower the resolution on the Monitor so it runs in 1080p, I'm mainly getting a 4K monitor for future gaming so I don't have to buy another monitor when I buy another computer in the next two or three years.

 

[exroofer]

I went with a 34' 3440 x 1440 ultrawide. Older games that don't support that will play in 16 x 9.
But pretty much all of my games will play at 21 x 9. Fallout 4 needed some modding.

This resolution and aspect ratio gives you a wider field of view, and high pixel density so it looks REALLY good.
But is substantially easier to drive than 4k. Good monitors are expensive, and at 4k or 3440 x 1440, you will want a GSync, (or Freesync), panel really. Variable refresh rate does wonders for high resolution games, making dips below 60fps pretty much not noticeable.

I currently drive it with my R290x at "acceptable" fps, with a few game setting tweaks. As in 50 -70 fps in the majority of my games. Freesync helps this remain smooth in game. Your 1080 is substantially faster.

Just something to consider, I got the LG 34UM88C Freesync, which is a 60HZ monitor by default. Before I bought it I knew that I could overclock it to 75HZ and increase the Freesync range from 40-60 to 35-75.
Which I immediately did lol.
There are now several 100HZ 3440 x 1440 monitors on the market.
Most benchmarks I see show even the mighty 1080ti having trouble hitting 60fps @ 4k in a lot of games.