I have noticed lately that the second Dual Graphics card is not showing up on my 6-Core Mac Pro 2013. I have forgotten if this has always been the case or has it changed with macOS Sierra? Did both cards show up in earlier OS's? I have questioned the performance lately on the dual GPU...if it is still duplexing, switching or combining when the GPU load get high during video production. I did not have one of the faulty GPU's, but notice on occasion a flicker on my thunderbolt monitor (maybe when the "Automatic Graphics Switching" kicks in if it still does it). Ever since Apple admitted the issues with the Mac Pro 2013 GPU heating problems back in April 2017, I have questioned if they made some driver or software changes in how the cards perform after? I remember Craig stated that they realized also that a single strong GPU is better than two combined (summary). I hope that Apple has not separated the dual GPUs functioning now since they still sell the Mac Pro 2013 - one for the monitors and one for processing due to all of the issues with the unit. I don't need a dedicated 3 GB JUST for the monitor and bought the trash can just for the dual cards... I hope that is not the case....10 months before I paid $1,300 more for my 6-Core Mac Pro 2013 (working in another country) and then they lowered the price $1,000...puts more salt in the wounds... Now the Mac Pro 2013 acts like an overpriced iMac without the monitor if they stopped the dual functioning GPU cards... Appreciate any thoughts if you have a Mac Pro 2013. Thanks!