Apple's 2019 Mac Pro is now three PCIe revisions behind

The PCI Express 6.0 standard has officially made its debut, meaning that Apple's Mac Pro — released in 2019 — is now several generations behind what's currently available.

On Tuesday, PCI-SIG — the organization responsible for PCIe — announced the official release of PCIe 6.0. The new revision brings a multitude of updates and new features to the expansion bus standard.

New features of the specification include a 64 GT/s raw data rate, mechanisms to mitigate bit error rate, updated packet layout in Flit Mode, and Pulse Amplitude Modulation with 4 levels. PCIe 6.0 is also backwards compatible with previous generations of the technology.

Apple's Mac Pro features PCIe expansion slots for graphics modules, I/O cards, and other upgrades. However, the Mac Pro remains on PCIe 3.0 — a specification that was first made available in 2010.

Since then, the PCIe 4.0 revision became ready to use by hardware manufacturers around June 2017. PCIe 5.0 was made available in November 2019, and the draft PCIe 6.0 specification was first announced in February 2020. As of January 2022, the specification should now be ready to include in hardware.

Apple is largely thought to be working on a Mac Pro update that moves the line over to custom Apple Silicon. Reportedly, the professional workstation could sport a 32-core M-series processor.

Additionally, Apple is also reportedly developing a smaller Mac Pro model.

It's not yet clear if either model will have PCIe slots. There are PCIe drivers available for some upgrade cards for Apple Silicon, but they are the exception rather than the rule. Drivers are what's preventing eGPU compatibility with Apple Silicon, as the cards and eGPU enclosures are recognized by Apple Silicon Macs over Thunderbolt.

Although the PCIe 6.0 specification is now available, it will take time before it's adopted by computer manufacturers and makes its way to consumers. If the timeline for previous revisions holds true, the first PCIe 6.0 hardware will arrive at about this time in 2023.

46 Comments

Dr.MORO 10 comments · 7 Years

About 2 years ago

Hi all,
Just an amateur question.
Thunderbolt 3/4 is compatible to carry PCIe of what specification or lower at this moment?
And is Thunderbolt 3/4 capable of carrying this new PCIe 6.0 specification at this moment hardware-wise, or needs some better hardware like Thunderbolt 5 in the future?
And also the same question with Apple M1 CPU architecture able to handle PCIe 6.0 hardware-wise, just with software tweaks, or need to wait for new and better Apple CPU of the future?
Just interested.
Thanks.

therunningvm 96 comments · 8 Years

About 2 years ago

Upgrading to these new PCIE standards doesn't make much sense, since most devices you'd use are not bandwidth limited.

sflocal 6138 comments · 16 Years

About 2 years ago

Dr.MORO said:

Hi all,
Just an amateur question.
Thunderbolt 3/4 is compatible to carry PCIe of what specification or lower at this moment?
And is Thunderbolt 3/4 capable of carrying this new PCIe 6.0 specification at this moment hardware-wise, or needs some better hardware like Thunderbolt 5 in the future?
And also the same question with Apple M1 CPU architecture able to handle PCIe 6.0 hardware-wise, just with software tweaks, or need to wait for new and better Apple CPU of the future?
Just interested.
Thanks.

The current Thunderbolt spec provides 40gb/s bandwidth. While fast, it's still far below PCIe 3.0 max of 32GB/s. I don't see a time where Thunderbolt will be at the same speed as the native PCIe bus.

The PCIe 6.0 specification I think will be geared more for servers than for consumer PC's. It involves some pretty expensive tech, and motherboard fabrication to handle those high speeds which is why it will be limited to servers, render-farms, etc..

rob53 3312 comments · 13 Years

About 2 years ago

sflocal said:

Dr.MORO said:

Hi all,
Just an amateur question.
Thunderbolt 3/4 is compatible to carry PCIe of what specification or lower at this moment?
…

The current Thunderbolt spec provides 40gb/s bandwidth. While fast, it's still far below PCIe 3.0 max of 32GB/s. I don't see a time where Thunderbolt will be at the same speed as the native PCIe bus.
The PCIe 6.0 specification I think will be geared more for servers than for consumer PC's. It involves some pretty expensive tech, and motherboard fabrication to handle those high speeds which is why it will be limited to servers, render-farms, etc..

In other words, there’s nothing really wrong with the version Apple used in the 2019 Mac Pro. Apple didn’t put any devices in the Mac Pro that would economically benefit from PCIe 4/5/6 so author is complaining about nothing.

killroy 286 comments · 17 Years

About 2 years ago

rob53 said:

sflocal said:

Dr.MORO said:

Hi all,
Just an amateur question.
Thunderbolt 3/4 is compatible to carry PCIe of what specification or lower at this moment?
…

The current Thunderbolt spec provides 40gb/s bandwidth. While fast, it's still far below PCIe 3.0 max of 32GB/s. I don't see a time where Thunderbolt will be at the same speed as the native PCIe bus.
The PCIe 6.0 specification I think will be geared more for servers than for consumer PC's. It involves some pretty expensive tech, and motherboard fabrication to handle those high speeds which is why it will be limited to servers, render-farms, etc..

In other words, there’s nothing really wrong with the version Apple used in the 2019 Mac Pro. Apple didn’t put any devices in the Mac Pro that would economically benefit from PCIe 4/5/6 so author is complaining about nothing.

Just a note here, The M1 CPU is PCIe 4.