Help! Mac Pro with AMD FirePro D500 - Strange issue with monitor

Hi, I didn't know where else to post this so I'm gonna try my luck here.

I have a 2013 Mac Pro with a AMD FirePro D500 graphics card. My monitor is a Seiki Pro SM40UNP 40 inch, 4K display. Before the Seiki, I had an LG 34UC97 Ultra-wide display.

There's something I'm noticing on the Seiki that I didn't on the LG. The Seiki is set to 3840 x 2160. Please bear with me as I don't know all the technical terms. When I'm working, sometimes I'll see the dots/pixels on the screen for a split second. This happens all day long. The dots/pixels are extremely tiny and I don't always see them, but it's such an annoyance. I don't know how to fix this problem and I'm surprised Seiki would have released something like this.

I'm using a 15 foot DisplayPort cable. On the Mac Pro, I have the DisplayPort cable connected to a Cable Matters adapter DisplayPort to Mini DisplayPort.

I know the LG is an IPS display and the Seiki is not. Does anyone know what's going on and if there's a way to fix this?

I posted a picture and dots/pixels look similar to that.

Any help would be truly appreciated.

Thanks!