MacBook Pro with (x4 < Thunderbolt 4 eGPU's)?

[McCutch]

I want to know if the MacBook Pro late 2016 or newer with Four Thunderbolt ports can have four eGPU's with RX580's in Crossover? Or even iMac with Four Thunderbolt4 ports? 

[Crunchy Dragon]

Can you even to a 4 way Crossfire?

 

That being said, you could technically connect 4 GPUs, yes.

[Drak3]

You can connect 4 GPUs, but each one will only have a x2 connection. The 4 ports are 2 ports per Thunderbolt controller, and a thunderbolt controller can only get a x4 connection.

8 minutes ago, Crunchy Dragon said:

 

Can you even to a 4 way Crossfire?

 

Not in OS X, and almost guarantee not over Thunderbolt.

 

 

[Kyle_N]

I believe you only get 4 (maybe 8) PCIe lanes, so performance would certainly be limited. A single GPU may already be bottlenecked by Thunderbolt's limited PCIe.

 

Technically possible but it's not really good for much.

[DrMacintosh]

Really just having one would give you the best performance. Thunderbolt is limited to a set amount of PCIE lanes. 

[Glenwing]

The ports are connected in pairs, if you put a high performance device in one port it will disable or severely limit the second port.

[Drak3]

5 minutes ago, DOGC_Kyle said:

I believe you only get 4 (maybe 8) PCIe lanes, so performance would certainly be limited. A single GPU may already be bottlenecked by Thunderbolt's limited PCIe.

 

Technically possible but it's not really good for much.

Not knowing the routing, and being to lazy to look it up.

7700HQ, the base proc on the 15" MBP, has 16 lanes from CPU. Chipset offers additional, not sure how many.

NVMe SSD runs an x4 connection, if you have a Radeon Pro 555 or 560, that takes a x8, two TB3 controllers, taking a x4 and a second x4. Total of 20, if the NVMe SSD is using chipset lanes, and only TB and dGPU takes up CPU, everything is happy.

3 minutes ago, Glenwing said:

The ports are connected in pairs, if you put a high performance device in one port it will disable or severely limit the second port.

The controllers can easily manage doing x2/x2.

[DocSwag]

18 minutes ago, Drak3 said:

The controllers can easily manage doing x2/x2.

That's his point, going to x2 could hamper performance.

[Drak3]

3 minutes ago, DocSwag said:

That's his point, going to x2 could hamper performance.

I wouldn't constitute that as severely limiting performance for high performance devices across the board, most current GPUs, yes. Other things, no.

[DocSwag]

9 hours ago, Drak3 said:

I wouldn't constitute that as severely limiting performance for high performance devices across the board, most current GPUs, yes. Other things, no.

Yeah but op is talking about using GPUs so...

[Barakaki]

I don't know about running 4 eGPUs but just for fun I have successfully ran 2 GTX1070 in 2 eGPU enclosure Daisy chain on a 2016 13" MBP running Sierra with a huge increase in performance. (Yes, knowing that the 13" MBP has no dedicated graphics onboard)

 

Please note: With the very little detail documentation  publicly released regarding both Apple's hardware & software implementation and not taking the time to break down every variable and  retesting the validity of my observation and speculation within my on personal experience. That said

 

With Apple's own proprietary  implementation regarding both Thunderbolt 2 and Thundebolt 3. I personally believe that Apple's Hardware Acceleration integration control has a lot of effect pertaining to distrabuation of the PCIe bus lanes. 

 

Testing the new Apple eGPU developer kit on the new 2017 15" MBP running High Sierra http://iphone.appleinsider.com/articles/17/06/06/apple-egpu-dev-kit-requires-external-monitor-nothing-unique-about-graphics-card-or-enclosure I've noticed that there was a huge performance differential with an AMD RX580 included with Apple's DevKit with taking the exact RX580 into a Akitio Thunder3 eGPU. And when combining both egpus together one the devkit would be recognizee.   With alot of Researching (via YouTube) found this arrival from 9to5mac https://9to5mac.com/2017/04/19/akitio-node-gtx-1080-ti-gpu-macbook-pro-gaming-egpu/ 

 

Switching to a 13" 2013 MBP running osSierra, I took a couple of GTX1070 and with the Akitio eGPU first I loaded the script referenced from 9to5mac in the command line. Once everything was restated I then added Apples DevKit with the second GTX1070  Daisychained after the Akitio. As soon as my Mac recognizes the DevKit and restart (not plug n play) connected an external monitor daisychained after DefKik surprisingly had a signal. 

 

Not having run any benchmarks,  can only comment In regards to video rendering and an improvement in times not only to just adding a single 1070eGPU to a MBP will be boosted but an addition of a second 1070eGPU added a signicant amount of performance with a big decrease in overall lag.