GPU update

Hi,

I have a Mac Pro 4,1 (early 2009) running on OS X 10.10.5 with a NVIDIA GeForce GT 120 512 MB GPU.

As a photographer I'm working with Lightroom and Photoshop, but these programs are running quite slow because the GPU doesn't give optimal support anymore.

Q: Is it possible (or a good option) to replace this slow GPU with the MSI GeForce GTX 970 4G GAMING? And if not, what could be another graphic card option to speed up my Mac?

These are the specs:

Mac Pro 4,1

Processor Quad-Core Intel Xeon

Processor speed 2,26 GHz

Processors 2

total cores 8

L2-cache (per core) 256 KB

L3-cache (per processor) 8 MB

Memory 32 GB 1066 MHz DDR3 ECC

Interconnect speed processor 5.86 GT/s

Thanks in advance! Hans