I'll show my ignorance.........

[Oldmanmac]

I have a 2015 27" iMac. System software shows PCI. Do I have an accessible PCI? Lots pf neat peripherals available.

 

[sublunar]

I have a 2015 27" iMac. System software shows PCI. Do I have an accessible PCI? Lots pf neat peripherals available.

In a word, no. The PCIe bus is accessible by using Thunderbolt 2 so you'll have access to fast external storage but not (official) eGPU.

 

[Oldmanmac]

So, my access is limited to Thunderbolt 2 only?

 

[Fishrrman]

The "PCI" that you see represented is kind of a "vestige" from back in the time when Macs actually came with "slots" into which you could plug expansion cards.

That time is "pretty much past" (we'll see if it changes when the new Mac Pro's come out).

If you wanted to use a PCI-based card today, I think you'd have to buy an "expansion chassis" which connects via thunderbolt, and go from there. Not even sure if such stuff still exists. And if it does, I'm going to -guess- that the options for what can be connected are pretty narrow.

What do you "have", that you need to "connect to"...?

 

[theluggage]

So, my access is limited to Thunderbolt 2 only?

Thunderbolt is partly based on the PCIe protocol - Thunderbolt peripherals use PCIe internally to drive PCIe-based disc/USB/whatever controllers.

You can get external PCIe expansion boxes that connect via Thunderbolt and accept PCIe cards.

E.g.: https://www.sonnettech.com/product/echoexpress3d.html (an example picked from the web - not an endorsement)

Generally, though, they're expensive - only economical for high-end PCIe cards like specialist video/audio digitisers and 10Gb+ Ethernet interfaces.

 

[Oldmanmac]

I had been looking at TB3 drives that looked as ifvcthey'd be less expensive thru the PCI.