Graphics card Radeon PRO W6600X

“Graphics card Radeon PRO W6600X: Hello, I purchased a Radeon PRO W6600X 8 GB graphics card from Apple for my 2019 Mac Pro. It came with the Pro 580X as the default card. I would like to know if the two cards can work simultaneously to share the graphics workload, or if I need to adjust settings to optimize their performance. Thank you!”

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Confirm Compatibility:

Research the manufacturer, and see what it says for device requirements. 2019 Macs’ hardware are all designed to operate as one device, and cannot be altered. So, no, that would not be an option.

getting two graphics card to work together is a very complicated, fiddly job, and has to be repeated for each and every software package you want to use. Many packages will never use both.

some users say, "I want the second card to lighten the load of drive-ing multiple displays."

But the load on the system of driving more displays is trivial -- data rates are so fast it must all done by Hardware Automata that automatically fetch the characters and produce the serial data stream. The CPU and GPU do next-to-nothing to support additional displays.

I recommend you go forward with ONLY the most-capable graphics card in the machine, and set the other aside as a spare or try to sell it.