Late 2016 MacBook Pro 13" + Thunderbolt 3 eGPU

rwstgermain

macrumors member
Sep 15, 2016
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I got the TB3-TB2 adapter this morning and can confirm eGPU is possible. It's not plug-n-play but automate-eGPU should work.

View attachment 669211
How is the switching between dGPU and eGPU preformed? Automatically once the eGPU is detected? I have been wondering if the Razer Core, which naively utilizes Thunderbolt 3, would just work within bootcamp.
 

cube

macrumors P6
May 10, 2004
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It seems you have to just hope macOS will select the right GPU.

Now it is doing it fine with iGPU, AMD 6xxx and AMD RX installed.
 

theitsage

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My understanding of a Mac with multiple GPUs in Mac OS environment is as followed:

- OpenCL apps (such as FCPX, Luxmark, Handbrake,..) are able to detect and make use of all GPUs.
- OpenGL apps (such as AutoCAD, Adobe CC, video games,...) run on the monitor through which the GPU is connected.

On a headless Mac like the Mac Pro, it's very simple to visualize how this GPU selection process works. Mac laptops with both iGPU and dGPU rely on Automatic Graphics Switching. I'm not smart enough to give a definitive explanation on how this works with an eGPU. I know using an external monitor is one sure way to take advantage of an eGPU for OpenGL/Metal tasks.
 
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cube

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A certain setup might not be running properly. I had the CPU or internal GPU rendering and displaying via the eGPU at some point.
 

theitsage

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I learned something new about ThunderBolt 3 bandwidth and how Apple might have crippled these 2016 MacBook Pros - https://thunderbolttechnology.net/sites/default/files/Thunderbolt3_TechBrief_FINAL.pdf

Apple talked about Thunderbolt 3 capable of 40 Gbps but due to the single Thunderbolt chip in the base MBP, each USB-C port can only run at 20 Gbps max. This is the same max bandwidth as Thunderbolt 2.

I would guess the 13" touchbar MacBook Pro is the same way - two Thunderbolt 3 chips handling 4 ports.
 
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Clint_Barton

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Oct 23, 2016
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I learned something new about ThunderBolt 3 bandwidth and how Apple crippled these 2016 MacBook Pros - https://thunderbolttechnology.net/sites/default/files/Thunderbolt3_TechBrief_FINAL.pdf

Apple talked about Thunderbolt 3 capable of 40 Gbps but due to the single Thunderbolt chip in the base MBP, each USB-C port can only run at 20 Gbps max. This is the same max bandwidth as Thunderbolt 2.

I would guess the 13" touchbar MacBook Pro is the same way - two Thunderbolt 3 chips handling 4 ports.
The information from apple says that the base-no touchbar provides full performance to both TB3 ports, while on the 13-touch bar, only the two left hand TB3 ports operate at full speed, while the right two are limited, the 15in has full performance on all ports.

From apple
"
Thunderbolt 3 data speeds per MacBook Pro port

Late-2016 MacBook Pro models vary slightly in the data speeds they provide to each Thunderbolt 3 port.

MacBook Pro (15-inch, Late 2016) delivers full Thunderbolt 3 performance on all four ports.

MacBook Pro (13-inch, Late 2016, Four Thunderbolt 3 Ports) supports Thunderbolt 3 at full performance using the two left-hand ports. The two right-hand ports deliver Thunderbolt 3 functionality, but have reduced PCI Express bandwidth.

Always plug higher-performance devices into the left-hand ports on MacBook Pro (13-inch, Late 2016, Four Thunderbolt 3 Ports) for maximum data throughput.

MacBook Pro (13-inch, Late 2016, Two Thunderbolt 3 Ports) delivers full Thunderbolt 3 performance on both ports.

About USB speed
For USB devices, all late-2016 MacBook Pro models deliver USB 3.1 Gen 2 (10 Gbps) performance on all Thunderbolt 3 ports.

Use a USB-C to USB adapter to connect a USB-A device or cable to a Thunderbolt 3 port on your MacBook Pro. Use a USB 3.1 (USB-C to USB-C) cable to connect a USB-C device."
 
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theitsage

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The support document talks about reduced PCIe lane. Here's what I'm seeing in Thunderbolt under System Information.

Screen Shot 2016-10-31 at 7.01.37 PM.png
 

Zackmd1

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Oct 3, 2010
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That would be absolutely amazing if true..... Also false advertising on Apple's part. Maybe this could just be an oversight in the hardware browser and the TB3 ports do indeed run at 40gb/s but its just reporting 20? Maybe? I would want to believe that over apple crippling the base model further but who knows anymore....
 

theitsage

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That would be absolutely amazing if true..... Also false advertising on Apple's part. Maybe this could just be an oversight in the hardware browser and the TB3 ports do indeed run at 40gb/s but its just reporting 20? Maybe? I would want to believe that over apple crippling the base model further but who knows anymore....
Someone has tried a Razor Core using a TB3 cable and see the same result. - http://imgur.com/hTrMsKY
 

killawat

macrumors 65816
Sep 11, 2014
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Thanks again for the quick reporting. Akitio needs to send you a Node so you can convince us to buy it.
 

Zackmd1

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Oct 3, 2010
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Someone has tried a Razor Core using a TB3 cable and see the same result. - http://imgur.com/hTrMsKY
Apple has gone to a new low with these MacBook's but false advertising is something else entirely.... There must be another answer.... I hope there is another answer.
[doublepost=1477965932][/doublepost]
eGPUs working makes or breaks the MBP purchase for me, thanks for looking into this guys
eGPUs seem to work but now the question seems to be whether or not they will run at TB3 40gb/s or the older TB2 standard of 20gb/s which is what the hardware is reporting....
[doublepost=1477966695][/doublepost]I started a thread here: http://forums.macrumors.com/threads/calling-all-2016-rmbp-owners.2011425/

I want to see if we can get more owners to report in on what their hardware browser says and if we can get anyone to test with actual TB3 accessories.
 

tryrtryrtryrt

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Sep 10, 2016
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The support document talks about reduced PCIe lane. Here's what I'm seeing in Thunderbolt under System Information.
Could you tell exactly what cable are you using? AFAIR only optical cable which is not capable of transferring energy can achieve 40 Gbps. All others can only achieve 20 Gbps. Need to dive into Thunderbolt 3 specs though, I'm not sure.
 

theitsage

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Could you tell exactly what cable are you using? AFAIR only optical cable which is not capable of transferring energy can achieve 40 Gbps. All others can only achieve 20 Gbps. Need to dive into Thunderbolt 3 specs though, I'm not sure.
2016 13" MacBook Pro --> Apple TB3 to TB2 Adapter --> Apple Thunderbolt 2 cable --> AKiTiO Thunder2 eGPU

I checked Thunderbolt in System Information on a mid 2015 15" MBP and a late 2015 27" iMac 5K.

Screen Shot 2016-11-01 at 6.01.08 AM.png


Screen Shot 2016-11-01 at 7.13.34 AM.png