1080 or 4K?

I was reading on another site that gaming on 2 1080x1920 monitors equals gaming in 4K.
is this correct?
or sorta, kinda correct?
even if it's sorta correct it would explain why I get lower frame rates than the reviews.

You would need 4 1920x1080 monitors to reach 3840x2160.

2 1090x1080 is 2k. and no, a 4k display will look far crisper than any multi monitor setup. as far as a fps hit goes, possibly, if it's driving two different video signals, the strain on the video card is higher.

4k is a little raw yet in my opinion, for gaming anyway. Even the newest top end card on the market right now can't give a solid 60fps in games @ Ultra settings, and even struggles to keep it's head above the 60hz water mark @ Very High settings in some titles from what I see on youtube. Personally, I wouldn't shoot for a high end gaming setup with 4K right now. I've made similar mistakes in the past. What you end up doing is giving up so much of what High end gaming has to offer, in exchange for more pixels.

Its not remotey like 4k. As jr said, you need four to get 3840x2160.

Also, 2k = 2048x1080. 2x 1920x1080 monitors is 3840x1080.

As far as 60 fps at 4k. A 1080 or 1080 ti can run a lot of titles there with high or ultra or settings...especially without, or low (2x), AA...or TXAA.

My Titan X Pascal runs 4K on max settings. Worst frame rate I get is 55 fps in a crowded town in The Witcher 3.

I would get a QHD 1440p monitor that can do 90 Hz or above instead. That will still look really good, you'll get above 60 FPS which is nice, it will cost less money, and you can easily find GPUs to run at that resolution. Even a 1070 is enough to run all max settings on QHD and still lock out 75 FPS+ on most games.