Grumble grumble. Well, there used to more than audio cards, back before the first time Apple canceled the Mac Pro and released the 2013 Studio^H^H Trash Can^H^H Mac Pro.
Then everyone stopped writing Mac drivers because why bother. So when they brought the PCIe Pro back in 2019, there wasn't much to put in it besides a few Radeon cards that Apple commissioned.
The nice thing about PCIe is the low latency, so you can build all sorts of fun data acquisition and real time control applications. It's also much cheaper because you don't need multi-gigabit SERDES that can drive a 1m line. That's why LabVIEW (originally a Mac exclusive) and NI-DAQ no longer exist on Mac.
USB-C oscilloscopes work because the peripheral contains all the hardware, so it doesn't particularly matter that the device->host latency is high. They also don't require much bandwidth because triggering happens inside the peripheral, and only the triggered waveform record is sent a few dozen times per second.
> It's not the Mac's or Apple's fault. We are actually live in the age where systems are quite independent and do not require direct installations.
It is, and we don't. Maybe you don't notice it, but others do.
Yeah, that's basically the way accessories have gone. Powerful mcu's and soc's have gotten cheap enough to make it viable. Makes me a little sad though, I liked having low latency "GPIO's" straight to software running on my PC (but I'm thinking as far back as the parallel port... love how simple that was).
With USB4/TB you can get quite far in both latency and throughput. Actually there are network adapters with TB connection that are just TB to PCIe adapters and PCIe network card.
My GPU, NVMe drives and motherboard might disagree.
This is an RTX4080.
“In the more common situations of reducing PCI-e bandwidth to PCI-e 4.0 x8 from 4.0 x16, there was little change in content creation performance: There was only an average decrease in scores of 3% for Video Editing and motion graphics. In more extreme situations (such as running at 4.0 x4 / 3.0 x8), this changed to an average performance reduction of 10%.”
Still, 10% in difference is still considerable, almost gen-to-gen difference
…so what do you actually need PCIe for?
Thunderbolt is also too slow for higher-end networks. A single port is already insufficient for 100-gigabit speeds.
Apple recently added support for InfiniBand over Thunderbolt. And now almost all decent Mac Studio configurations have sold out. Those two may be connected.
TIL:
* https://developer.apple.com/documentation/technotes/tn3205-l...
Or maybe I forgot:
If you use dual-port NICs, you do not need a high-speed switch, which may be expensive, but you can connect directly the computers into a network, and configure them as either Ethernet bridges or IP routers.
I suppose that splitting an LLM workload is pretty sensitive to that.
Multi-GPU has recently experienced a resurgence due to the discovery of new workloads with broader appeal (LLMs), but that's too new to have significantly influenced hardware architectures, and LLM inference isn't the most natural thing to scale across many GPUs. Everybody's still competing with more or less the architectures they had on hand when LLMs arrived, with new low-precision matrix math units squeezed in wherever room can be made. It's not at all clear yet what the long-term outcome will be in terms of the balance between local vs cloud compute for inference, whether there will be any local training/fine-tuning at all, and which use cases are ultimately profitable in the long run. All of that influences whether it would be worthwhile for Apple to abandon their current client-first architecture that standardizes on a single integrated GPU and omits/rejects the complexity of multi-GPU setups.
I/O expansion
Networking
Thunderbolt is external PCIe.
Thunderbolt can kinda-sorta mimic PCIe, but it needs to chop up the PCIe signal into smaller packets, transmit them and then put them back together and this introduces a big jump in latency, even when bandwidth can be rather high.
For many applications this isn't a big deal, but for others it causes major problems (gaming being the big one, but really anything that's latency sensitive is going to suffer a lot).
This is a wild and very wrong take.
Just about every single consumer computer shipped today uses PCIe. If you were referring to only only the physical PCIe slots, that's wrong too: the vast majority of desktop computers, servers, and workstations shipped in 2025 had physical PCIe slots (the only ones that didn't were Macs and certain mini-PCs).
The 2023 Mac Pro was dead on arrival because Apple doesn't let you use PCIe GPUs in their systems.
That's what happens when you quote only part of a statement. Taken in context, it was referring to a very real decline in expansion cards. Now that NICs (for WiFi) and SSDs have been moved into their own compact specialized slots, and Ethernet and audio have been standard integrated onto the motherboard itself for decades, the regular PCIe slots are vestigial. They simply are not widely used anymore for expanding a PC with a variety of peripherals (that era was already mostly over by the transition from 32-bit PCIe to PCIe).
Across all desktop PCs, the most common number of slots filled is one (a single GPU), and the average is surely less than one (systems using zero slots and relying on integrated graphics must greatly outnumber systems using more than one slot).
Even GPUs themselves are a horrible argument in favor of PCIe slots. The form factor is wildly unsuitable for a high-power compute accelerator, because it's ultimately derived from a 1980s form factor that prioritized total PCB area above all else, and made zero provisions for cards needing a heatsink and fan(s).
Unless the one it comes with isn't as fast as the one you want, or they didn't integrate one at all, or you need more than one.
> Across all desktop PCs, the most common number of slots filled is one (a single GPU), and the average is surely less than one (systems using zero slots and relying on integrated graphics must greatly outnumber systems using more than one slot).
There is an advantage in having an empty slot because then you can put something in it.
Your SSD gets full, do you want to buy one which is twice as big and then pay twice as much and screw around transferring everything, or do you want to just add a second one? But then you need an empty slot.
You bought a machine with an iGPU and the CPU is fine but the iGPU isn't cutting it anymore. Easy to add a discrete GPU if you have somewhere to put it.
The time has come to replace your machine. Now you have to transfer your 10TB of junk once. You don't need 100Gbps ethernet 99% of the time, but using the builtin gigabit ethernet for this is more than 24 hours of waiting. A pair of 100Gbps cards cuts that >24 hours down to ~15 minutes. If the old and new machines have an empty slot.
He's not advocating from removing PCIe slots, but in practice, it's needed by way less consumers than before. There's probably more computers being sold right now without any PCIe slot than there are with more than 1.
Discrete GPUs generally consume two PCI slots, not three, and even the mATX form factor allows for four PCI slots (ATX is seven), which gives board makers an obvious thing to do. Put one x16 slot at the top and the other(s) lower down and use the space immediately under the top x16 slot for an x1 slot which is less inconvenient to block or M.2 slot which can be used even if there is a GPU hanging over it. This configuration is currently very common.
It also makes sense to put one of the x16 slots at the very bottom because it can either be used for a fast single height card (>1Gb network or storage controller) or a GPU in a chassis with space below the board (e.g. mATX board in ATX chassis) without blocking another slot.
I don't see it disappearing, at most we'll get PCIe 6/7/etc.
I don't understand how this is a response to anything I said.
With USB3 you have 94 i/o…
For years pci has not been mandatory for audio. UAD, Apogee, RME and other high end brands will push you to them. Or even only provide them as usb device… even Thunderbolt is not needed here.
And that’s been the case for a while! My Fireface UC from 15 years ago can deal with 16 channels at 96khz at 256 sample. On PC and Mac.
Incredible products, definitely worth the premium.