Question Help me select the best Gaming monitor for my GPU

I get the feeling you're confusing two particular things: 'refresh rate' and 'frames per second'.

Refresh rate is for the monitor, eg. 60Hz, 120Hz, 144Hz, etc.

Frames per second will be dependent on the system's hardware. More crucially it will mostly be determined by the CPU and GPU. Best analogy is drawing a picture. The CPU draws the lines of the frame, while the GPU fills in the lines. And even then we're ignoring the actual game itself.

That said, I'm of the opinion that fps being greater than refresh rate is more preferable than the other way around. But for people to help you you'd need to list your specs. (The graphics card already doesn't match what's in your signature.)
 
I get the feeling you're confusing two particular things: 'refresh rate' and 'frames per second'.

Refresh rate is for the monitor, eg. 60Hz, 120Hz, 144Hz, etc.

Frames per second will be dependent on the system's hardware. More crucially it will mostly be determined by the CPU and GPU. Best analogy is drawing a picture. The CPU draws the lines of the frame, while the GPU fills in the lines. And even then we're ignoring the actual game itself.

That said, I'm of the opinion that fps being greater than refresh rate is more preferable than the other way around. But for people to help you you'd need to list your specs. (The graphics card already doesn't match what's in your signature.)

My CPU is Ryzen 7 1700 box 8 gb ram the gpu is Sapphire RX570 Nitro+ 8GB. I was pretty clear in my post, i was asking what's the maximum refresh rate i can get with this specs on my gpu, in 1920x1080 resolution. In a site i read the maximum refresh rate on this resolution with this GPU, is 60 Hz. So what should i buy ?? a 75Hz monitor or a 144Hz or maybe is an overkill the 144Hz ? Will i achieve this refresh rate according to my GPU ??
 
I'm afraid to say your reply shows you are still confusing the two terms which I sought to clarify with my initial post. I don't know where you read your specs are capped at 60Hz because that makes no sense.

You are asking what framerates your PC can generate; which will be game, resolution and graphical detail dependent. And framerates differ to the monitor's refresh rate.

Example 1: 200fps on Counterstrike with a monitor refresh rate of 60Hz. The monitor will only display 60 frames of the 200.
Example 2: 30fps on Ashes of the Singularity with a monitor refresh rate of 240Hz. The monitor will display all those generated frames (hopefully evenly paced).

With that in mind, you could get a 240Hz monitor and it will be supported. It doesn't mean it will be of best use though. That said, consider looking at benchmarks for the games you play to see what fps the components can deliver, and use that to inform your choice of the monitor's refresh rate.