This morning I was just checking my "About This Mac " PCI specs and was unpleasantly surprised to see that my Samsung 970 EVO was running at X 1. Link Width.
Then I remembered that I installed a new 2 port USB 3.1 2 card Link Width x 2. It was in PCIe slot 4
The Samsung 970 EVO was in PCIe slot 3.
I shut down and put the 970 EVO into slot 4 &. the USB 3.1 card into slot 3.
Did a cold startup with a TRIPLE NVMe reset.
Everything is back to normal with the 970 EVO running at x 4 Link width.
Blackmagic confirms it.
![BlackmagicDiskSpeedTest.png]( "BlackmagicDiskSpeedTest.png")
NOTE : Probably USB 3.0 ( not 3.1 ) cards will be OK in either PCIe slot 3 or 4 as most are x 1 Link Width while 3.1 cards. gernerally are at x2 Link Width.
Then I remembered that I installed a new 2 port USB 3.1 2 card Link Width x 2. It was in PCIe slot 4
The Samsung 970 EVO was in PCIe slot 3.
I shut down and put the 970 EVO into slot 4 &. the USB 3.1 card into slot 3.
Did a cold startup with a TRIPLE NVMe reset.
Everything is back to normal with the 970 EVO running at x 4 Link width.
Blackmagic confirms it.
NOTE : Probably USB 3.0 ( not 3.1 ) cards will be OK in either PCIe slot 3 or 4 as most are x 1 Link Width while 3.1 cards. gernerally are at x2 Link Width.