External Monitor issues with P377SM-A

I'm having issues with my new external monitors that I just purchased. When I try to plug them into the HDMI port, they register as a DVI-D connection. (This should be a regular HDMI to HDMI connection) and the result is the same after another cable, from my Nintendo Switch.
Now, this would be kind of fine if not for the fact that it won't let me use its advertised 75HZ or Freesync, only 60HZ. Now, knowing that my laptop only has one HDMI connection, but also a Thunderbolt 2 connector, I bought two DisplayPort Mini to HDMI cables from Rosewill off Amazon supposedly rated at DP 1.1A input and HDMI output.
The back of the packaging reads
"Support Mini DisplayPort 1.1a input and HDMI output
Support HDMI 225mhz/2.25Gbps per channel (6.75gpbs all channel) bandwith)
Support HDMI 12bit per channel (36bit all channel)
Powered from MDp source"
Except, when plugged into the thunderbolt port, and the monitor, it registers as HDMI connected to the monitor, and allows me to turn on Freesync and a bunch of other various bits, but still only 60HZ. Now, I bought this mainly for my P870DM-G when it arrives on Friday, and a little disappointed that it isn't working.

I am going to try the MDp to HDMI/ HDMI to HDMI cable on a HD 7770 system which has MiniDisplayPort and HDMI.

So, my question after all of this is, how do I enable 75HZ on these monitors?

(P377SM-A configuration is my signature)

Acer SB220Q bi 21.5" Full HD <- Monitor
(1920 x... https://www.amazon.com/dp/B07CVL2D2S?ref=yo_pop_ma_swf

Rosewill 6-Feet Mini DisplayPort HDMI <- cable https://www.amazon.com/dp/B00MGG1PZU?ref=yo_pop_ma_swf

Edit: I should mention that I was getting screen tearing at 60HZ when using them together in a MultiDisplay config, and after turning it off, same thing. Using CRU to reset the monitors solved it, as did setting it to 59HZ, so my assumption is that these mDP to HDMI don't have enough bandwith for 1080P 75HZ which is extremely annoying, as even my phone drives more bandwith than that

 

Alright, so update time. The HD 7770 allows it to run at 75HZ using a HDMI to HDMI, but not freesync. Using a mDP to HDMI, locked at 60HZ and still no freesync. I dont't honestly care too much about Freesync, but I do care about the 75HZ refresh rate.

 

The last thing I'm going to do with these cables is probably test a Macbook Air with thunderbolt 2 so I can see if its just my laptop, then I might wait for my P870DM-G to arrive and then probably return these

Edit: Couldn't be bothered to get it working, so I returned the monitors