Mac Pro 5.1 new Samsung monitor not working

Hi. So I finally decided to upgrade my monitor from a very old Hanns G to a very new Samsung LC27JG50QQUXEN. It's connected from my stock Apple graphics card DVI out to HDMI in the monitor. I've tried every port on the monitor and constantly connecting/reconnecting it and constantly restarting my mac.

It "works" to the extent that the screen stops looking for an input when I select "Detect Displays" but I've not seen anything from my fully booted computer on it. It actually displays my hard drive boot menu when I hold "alt" on start up.

The mac is Early 2009 running Sierra 10.12.6

Here's what I've tried so far:

Switching my firmware between 2009 and 2010. It's currently on 2010.

Different resolutions on my Hanns G monitor then connecting it to the Samsung. I’ve now changed it back to “Default for display”

Installed all available updates

Reset SMC

Reset NVRAM

Connected the display wth the correct HMDI port selected and clicked detect displays in Mac displays preferences

Downgraded DisplayLink to 4.3.1

If anyone can suggest a fix that may work it'd be greatly appreciated!

Here's some system info with the Hanns G connected. I can't pull up the same info with the Samsung connected

Hardware Overview:

 Model Name: Mac Pro

 Model Identifier: MacPro5,1

 Processor Name: 6-Core Intel Xeon

 Processor Speed: 3.33 GHz

 Number of Processors: 2

 Total Number of Cores: 12

 L2 Cache (per Core): 256 KB

 L3 Cache (per Processor): 12 MB

 Memory: 96 GB

 Processor Interconnect Speed: 6.4 GT/s

 Boot ROM Version: MP51.007F.B03

 SMC Version (system): 1.39f5

 SMC Version (processor tray): 1.39f5

 Serial Number (system): E710103G20G

 Serial Number (processor tray): J5948014L1LUE   

 Hardware UUID: EE8BD1A7-D398-5F7F-8F6E-6A87599E172E

NVIDIA GeForce GT 120:

 Chipset Model: NVIDIA GeForce GT 120

 Type: GPU

 Bus: PCIe

 Slot: Slot-1

 PCIe Lane Width: x16

 VRAM (Total): 512 MB

 Vendor: NVIDIA (0x10de)

 Device ID: 0x0640

 Revision ID: 0x00a1

 ROM Revision: 3386

 Displays:

HW191D:

 Resolution: 1440 x 900 @ 60 Hz

 Pixel Depth: 32-Bit Color (ARGB8888)

 Display Serial Number: 651GH3CY14282

 Main Display: Yes

 Mirror: Off

 Online: Yes

 Rotation: Supported

 Automatically Adjust Brightness: No