OSX Sierra support for Radeon R9 270 Graphic card

I am a Mac OSX Sierra user running on I7 6700 Skylake Processor at 3.41 Ghz and Gigabyte H170M-D3H based on Intel Z170 Chipset with 8 GB DDR4 Memory. I purchased a Radeon R7370 4 GB (which I found was actually the same as R9270 with sub vendor Asus) for my intel based PC to run on the same. I have to my dismay found that it runs with a Video ram of 4MB rather than the original 4GB capacity. I have edited the Clover Plist and added 4096 in the Vram section and ports to 4 but to no avail. But when I used the internal (Intel 530) graphics as the main display the Vram ( shared memory that I added) shows exactly what I added to it and all the 3 ports works fine.

Can anybody say what is wrong with the display card? I there a solution to it? Do I have to change the card itself?


Please give me the solution as soon as possible.


Thanks in advance