MacBook Pro freezes when hooking up external display

I have a mid 2012 MacBook Pro that is have problems with displaying the image onto an ASUS vx279q monitor. I am currently trying to connect via a thunderbolt mini display to display port cable and when hooking the connector in the MacBook it attempts to adjust resolution on the MacBook while displaying nothing on the ext monitor. The MacBook then proceeds to freeze requiring a press of the power button to reset it.

While a thunderbolt to hdmi dongle>hdmi cable>monitor did work at displaying to my monitor that port is now taken up by my xbox one fed through a splitter from living room through the attic and back down again. I would like to avoid another splitter and addition stuff on my desk. The Xbox one is also weirdly not compatible with display port.

Also my girlfriends MacBook Air (early 15) hooks to the monitor just fine using a thunderbolt to display port cable.

Her computer is factory fresh, while mine has had a recent hard drive replacement to a Samsung 850evo SSD with a fresh install of El Capitan because of the originals failure. I also increased ram to 8gb while I was in there if it makes any difference.

Both computers running El Capitan 10.11.4

These are all third party cables and connectors I bought at my local computer parts store. I even tried a hdmi>DisplayPort cable to hook to my existing thunderbolt>HDMI dongle and no dice. Same problem. So the third time I went back to the store for a new solution the guy pointed me to a thunderbolt to DisplayPort, he even hooked it up to a brand new display MacBook Pro (non retina) and the same monitor I recently purchased. It worked right off the bat.

Trying to have everything hooked up at start up ends in the same freezing result. Ive also tried resetting NVRAM and SMC to no avail.

Im unsure of how to identify whether this is a hardware issue with the laptop or desktop, or software problems with the thunderbolt..