Under 'Bus Interface', this time the specifications state 'PCI Express 2.0 x4', which means this card has a four lanes for data. Again, how the card preforms depends on the slot you use. This OWC website offers a Allegro USB-C 4-Port card for $149 (USD), which is also for your model Mac. If you use one of the PCIe slots in your Mac, then the transfer rate will be only 250 MB/s. So the actual transfer rate to the Mac will be the lower of the two which is the PCIe speed of 500 MB/s. According to the 'USB 3.2 transfer modes' table USB 3.1 Gen 1 (or USB 3.0) transfers data a 625 MB/s. According to the 'PCI Express link performance' table, if you put the card in the PCIe 2.0 slot, then the transfer between the card and the Mac will occurs at 500 MB/s. Under 'Bus Interface', the specifications state 'PCI Express 2.0 x1', where 'PCI Express means 'PCIe' and 'x1' means the card only has a single lane for data. However, how the card preforms depends on the slot you use.

This OWC website offers a Allegro USB 3.0 4-Port card for $59 (USD) and explicitly states the card is for your model Mac. Which means some cards may work in your Mac, but not necessary at at a high enough speed to get the performance advantages of USB 3. Wikipedia also has the table shown below.Īlmost everything made for PCIe and USB is as backward compatible as reasonably as possible. USB 3.0 adds the new transfer rate referred to as SuperSpeed USB (SS) that can transfer data at up to 5 Gbit/s (625 MB/s), which is about 10 times faster than the USB 2.0 standard.

Wikipedia offers a nice table which is repeated below.īelow is a quote from Wikipedia regarding USB 3.0. PCIe 1.1 has the same data rate as PCIe 1.0. Note: The two PCIe x4 expansion slots are actually PCIe 1.1 x4 expansion slots. Apple also reports that 'all slots provide mechanical support for 16-lane cards 300W combined maximum for all PCI Express slots.' This model has two PCIe x4 expansion slots and two PCIe 2.0 x16 expansion slots (in the default confugration one PCIe 2.0 x16 slot is occupied by the graphics card). The website reports the following (which basically is the same as Apple reports:

Pcie usb 3 card in pcie x4 slot