eGPU Design wrt GPU Performance

[WarthogARJ]

Hi,
I'm considering buying an eGPU to give me some flexibility with my "new" 2nd hand 27" iMac 2019.
Can anyone point me to a good overall review/discussion of eGPU's in general?

I'd like to be able to compare various eGPU against each other in terms of performance benchmarks.
I see an eGPU as a way to squeeze a bit more performance/life out of an older & inherently lower cost system.

This is perhaps the wrong audience to ask, because TPU is slanted heavily towards gaming, and Mac's have never tried to be good at aiming.
But the MAC ARM's are probably going to shake the tree there.

Just looking at the Sonnet eGPU so far, I see that their critical specs seem to be:
(1) Connection to Computer: Thunderbolt (3 or 4), or else USB-C
(2) Graphics Co-Processor:
AMD Radeon RX Vega 64 (Sonnet eGPU Breakaway Box 750)
or
AMD FirePro 2270 (Sonnet eGPU Breakaway Box 550): legacy product
(3) Dedicated power-supply with cooling fans: support 375W cards
(4) Various addtional outputs (varies from model to model):
Thunderbolt output (for daisychaining)
USB
HDMI (not Sonnet but other eGPU)
Ethernet
Extra power (>=80W)
(5) GPU compatibility:
Size: max physical size of GPU that can fit inside
Power: extra 8-pin connectors

I've got a couple of questions:
(1) What does the Graphics Co-Processor do?
If you used a Sonnet eGPU in an iMac, and plugged in an extra monitor to the iMac Thunderbolt, do you actually use the co-processor?

(2) What's the bottleneck in an eGPU system?
This obviously depends on how it's used, but any ideas on how performance would vary if you used something lke a MacPro 2012 as your benchmark system?
And ran the same GPU internally vs in the eGPU?

Or else in a Desktop PC?
Let's say Windows 10, where the GPU was run in the internal PCe slot compared to in an eGPU?

(3) Performance/cost comparison:
It would be VERY interesting to compare one of the newest Intel Macs with an eGPU vs a "roughly equivalent" Mac ARM M1/M2 system.
This obviously becomes a bit subjective to select the Mac ARM system to run it against, but if you restricted to overall price of new ARM system to that of the Intel with eGPU plus GPU, I wonder how it would compare?

Ideally in an 27" iMac 2019 with an intel 3.6 GHz i9-9900K 8 core, with lots of RAM (64GB or 128GB) vs an M1/M2 ARM system (either MacBook Pro or iMac).
The cost of the new Mac ARM systems incease DRAMATICALLY once you start to increase from the base OEM model.
And once selected, you CANNOT change it: zero flexiblity.

But the iMac 2019 allows you to vary components by a considerable degree:
- RAM: up to 128 GB for a very reasonable cost of
- SSD: 1 or 2
- GPU: internal Radeon Pro Vega 56 with the addition of a VERY big range of GPU's in an eGPU

You can buy a used 1 year old 27" iMac 2019 in pristine condition for +/- USD $2,500 specced as follows:
Intel 3.6GHz i9-9900K 8 Core
RAM: 128GB
SSD: 2 x 2TB (PCIe and SATA)
Internal GPU: Radeon Pro Vega 56
Monitor: 27" 5K Retina
eGPU: Sonnet with something like AMD Radeon RX 6800 XT or equivalent

New ARM Mac:
(a) MacBook Pro 13" for USD 2,500
M2 8-core CPU, 10 Core GPU
RAM: 24 GB
SSD: 2 TB

(b) Mac M1 Max Studio with Studio Display for USD 5,200
M1 Max: 10-Core, 24-Core GPU
RAM: 64 GB
SSD: 4 TB

You can obviously go between Option A and B considerably by buying a cheaper 3rd party display: the Studo Display is $1,600
And buy less RAM (32 GB) and less internal SSD (2TB).
That would give something like:
(C) Mac M1 Max Studio with good quality Samsung for USD $3,500
M1 Max: 10-Core, 24-Core GPU
RAM: 32 GB
SSD: 2 TB

I'm curious what the various benchmarks would be:
Synthetic: GeekBench 5 etc.
Standard gaming ones
Video processing/technical computing: Final Cut Pro, Matlab, Ansys etc.

Thanks,
Alan

 

[bonehead123]

I don't know about the rest of your questions, but the FirePro is a very OLD & OUTDATED (circa 2011) workstation-class GPU, which would be great IF you are doing workstation type of work with older apps, otherwise for gaming/everyday stuff, a more recent, consumer-grade card would surely serve you better overall....

 

[WarthogARJ]

Additional:
I bought my used 2019 Intel-based 27" iMac as a cost-effective way to have an Intel Mac with good specs.
Apple's move to ARM causes some issues wth running Intel-based software.
And I don't like Apple's overall hardware move to components you cannot easily repair let alone upgrade as a 2nd-hand owner.

A 2019 iMac with Montery (or Ventura) should have a supported life until 2027 or later.
And it's pretty flexible system: can boot into Windows or Linux, as well as run a large range of VM's.

It's not really a desktop, more like a laptop wthout a battery...:-}
But it has a big screen (for a laptop: 27"), and lots of outputs (4 x USB 3 plus 4 x Thunderblt 3).
And lots of RAM (up to 128GB), 8 cores and easily runs 4TB intenal SSD.

I don't know about the rest of your questions, but the FirePro is a very OLD & OUTDATED (circa 2011) workstation-class GPU, which would be great IF you are doing workstation type of work with older apps, otherwise for gaming/everyday stuff, a more recent, consumer-grade card would surely serve you better overall....

Thanks for reply.
Yes I know, but you need to either read the rest of the question, or else know something about eGPU's.

The Sonnet is designed to use a NEW GPU like GeForce RTX 3070 if you want.

The FirePro is NOT the actual GPU, but is called a Graphics CO-PROCESSR.

I'm not sure what its actual purpose is in the eGPU: which is why I asked.

I don't know about the rest of your questions, but the FirePro is a very OLD & OUTDATED (circa 2011) workstation-class GPU, which would be great IF you are doing workstation type of work with older apps, otherwise for gaming/everyday stuff, a more recent, consumer-grade card would surely serve you better overall....

Thanks for reply.
Yes I know, but you need to either read the rest of the question, or else know something about eGPU's.

The Sonnet is designed to use a NEW GPU like GeForce RTX 3070 if you want.

The FirePro is NOT the actual GPU, but is called a Graphics CO-PROCESSR.

I'm not sure what its actual purpose is in the eGPU: which is why I asked.

Looking at your System, I would think you could buy an eGPU and run a much more powerful GPU than an Iris Plus 655?
I'd say a MacMini and simlar is EXACTLY what eGPU's are aimed at.

An Intel CPU with Iris is MUCH less powerful than any of the new Apple ARM M1/M2 systems.
I'd be curious to see how your system performs on standard benchmarks versus the newer Apple ARM gear.

 

[bonehead123]

Usually, a "Co-processor" is intended to help with offloading some lower-priority, less-demanding tasks from the main GPU so it can deal with the heavier-duty stuff...

And FYI, I did read the entire post, and as stated, I did not comment on things that I am not well-versed in, like the potential performance improvements or comparisons between various systems/configs etc....

And FYI #2 - other than the connection methods to the host system (TB/USB vs. pcie), an eGPU is essentially the same as an internal dGPU, just moved out into an external enclosure...

Sorry if I upset or conflaberated you with my response... I was merely offering info I thought might help, but I will go & die under a rock now, thank you. Goodbye cruel world !

 

[WarthogARJ]

I don't know about the rest of your questions, but the FirePro is a very OLD & OUTDATED (circa 2011) workstation-class GPU, which would be great IF you are doing workstation type of work with older apps, otherwise for gaming/everyday stuff, a more recent, consumer-grade card would surely serve you better overall....

Hi,
Actually, your system is a good one to use as a Windows-based benchmark.
Have you ever run GeekBench on yours?
Or other benchmarks?

And what would it cost to buy your system now?
Have you ever considered using an eGPU to get a more powerful GPU capabilty?

Usually, a "Co-processor" is intended to help with offloading some lower-priority, less-demanding tasks from the main GPU so it can deal with the heavier-duty stuff...

And FYI, I did read the entire post, and as stated, I did not comment on things that I am not well-versed in, like the potential performance improvements or comparisons between various systems/configs etc....

And FYI #2 - other than the connection methods to the host system (TB/USB vs. pcie), an eGPU is essentially the same as an internal dGPU, just moved out into an external enclosure...

Sorry if I upset or conflaberated you with my response... I was merely offering info I thought might help, but I will go & die under a rock now, thank you. Goodbye cruel world !

Sure: I wasn't upset by it.
And the comment on what the Co-Processor does is indeed EXACLY what I was looking for.
Thanks.

But I don't understand how it is actually used in the eGPU design.
And how overall performance is affected by it.

For instance, you can by an older Sonnet design that uses the FirePro, and has sightly less power supply.
Or pay +/- $100 more and get the newer slightly bigger PSU model, with the Radeon RX Vega 64.

I didn't see the other eGPU types specifically mention a Co-Processer: maybe they don't use one?
Although the Razor says it has an "AMD Chipset"; maybe same thing?

I asked Mr. Google for background to eGPU design, and I don't see anything very useful.
The results are basically:
(1) Marketing repeats (as what's on TPU)
https://good-design.org/projects/blackmagic-egpu/

Sonnet Announces Professional Modular Thunderbolt Expansion for the Desktop and Rack

Sonnet Technologies today announced the DuoModo line of professional, modular Thunderbolt expansion systems for the desktop and for rack installation, the latest entries in its award-winning lineup of Thunderbolt products. The DuoModo line is comprised of three interchangeable expansion...

www.techpowerup.com

Sonnet Announces Professional Modular Thunderbolt Expansion for the Desktop and Rack

Sonnet Technologies today announced the DuoModo line of professional, modular Thunderbolt expansion systems for the desktop and for rack installation, the latest entries in its award-winning lineup of Thunderbolt products. The DuoModo line is comprised of three interchangeable expansion...

www.techpowerup.com

GIGABYTE Launches AORUS RTX 3090 and RTX 3080 GAMING BOX eGPUs

GIGABYTE, the world's leading premium gaming hardware manufacturer, today announced AORUS RTX 3090/3080 GAMING BOX, the world's 1st water-cooling external graphics. AORUS RTX 3090/3080 GAMING BOX is equipped with the most powerful NVIDIA Ampere architecture GeForce RTX 3090/3080 graphics card...

www.techpowerup.com

Sonnet EGFX Breakaway Box 750
Review: Blackmagic eGPU Pro – more powerful and capable, but who is it for

(2) Limited performance reviews

Sonnet introduces two higher-powered Thunderbolt 3 eGPU Breakaway boxes for Intel Macs

Sonnet eGPU Breakaway Box To Use External Graphics Cards via Thunderbolt 3BEST EGPU ENCLOSURES – OCTOBER 2022 EXTERNAL GPU BUYER GUIDE

Hands On With The Blackmagic eGPU
Review: Blackmagic Design's eGPU

Usually, a "Co-processor" is intended to help with offloading some lower-priority, less-demanding tasks from the main GPU so it can deal with the heavier-duty stuff...

And FYI, I did read the entire post, and as stated, I did not comment on things that I am not well-versed in, like the potential performance improvements or comparisons between various systems/configs etc....

And FYI #2 - other than the connection methods to the host system (TB/USB vs. pcie), an eGPU is essentially the same as an internal dGPU, just moved out into an external enclosure...

Sorry if I upset or conflaberated you with my response... I was merely offering info I thought might help, but I will go & die under a rock now, thank you. Goodbye cruel world !

I wonder if the "Co-Processor's" main purpose is just to provide some native external monitor outpout?
For example to allow you to run a pure graphics accelerator like a Tesla without any graphics output.

WRT "Usually, a "Co-processor" is intended to help with offloading some lower-priority, less-demanding tasks from the main GPU so it can deal with the heavier-duty stuff...", yes, I thought that MIGHT be the idea, but surely that needs a pretty good interface between the Co-Pocessor, CPU/Motherboard and the external GPU?

Intel says that Tunderbolt goes into a "PCH" (Peripheral Controller Header....I THINK is what that means).

As for #2, TB is theoreticallly FASTER than an Express Card interface native to the motherboard.
I might be looking at the rong rates here, so please correct me:
PCI Express 4: Transfer rate per lane 16.0 GT/sec, with PCIe 4.0 x 16 @ 31.508 GB/sec
TB 3: is a bit confusing (to me), but I believe it can be up to 40 GB/sec

And i'd be the last to say I understand it, but it seems the actual speeds of a TB 3 connection depend on the motherboard design.
As well as what is connected to it.

So I suspect that the ACTUAL performance of a GPU in a given eGPU can vary a lot depending on the system.
Which is why I think it needs some proper benchmark testing.

And I just found some better links, on the Wikipedia PCI_Express page:
External GPU's

There's a little bit of info on that, and it has a few references I'll read.
The Thunderbolt Devices Trickle In: Magma's ExpressBox 3T
MSI GUS II external GPU enclosure with Thunderbolt (hands-on)
Echo Express Pro: Desktop Graphics In A Thunderbolt Chassis
MSI to showcase 'GUS' external graphics solution for laptops at Computex Read more: https://www.tweaktown.com/news/15382/msi_to_showcase_gus_external_graphics_solution_for_laptops_at_computex/index.html
Fujitsu-Siemens Amilo GraphicBooster External Laptop GPU Released
2017 Razer Blade Stealth and Core V2 detailed Read More: https://www.slashgear.com/2017-razer-blade-stealth-and-core-v2-detailed-17504328/?utm_campaign=clip

Aha....OK, I see that there's a good technical discussion on Reddit: "eGPU".
I'll search that, and post my question there.

When i get some good feedback, I can post a link on TPU.

 

[cvaldes]

Read Sonnet's overview:

eGPU Breakaway Box 750/750ex - Sonnet

Thunderbolt eGPU enclosure for AMD and NVIDIA GPU cards and demanding PCIe cards. 750ex model includes USB 3.2 Gen 1 Type A ports and Gigabit Ethernet port.

www.sonnettech.com

which summarizes the primary reasons for considering an eGPU. If you don't do any of those things (you have never specified your actual usage case), forget the eGPU.

Your 27" iMac 5K 2019 already has a fairly capable video card so you'd have to stick a Radeon RX 5700 XT or RX 6800 XT to gain significant improvement.

No one sane would buy an eGPU+graphics card combo primarily for gaming on a desktop Mac. Any boost in gaming performance is a bonus but it's not cost effective to shell out all that cash because gaming is the primary goal. Just buy a console (Xbox, Playstation) and game on that: at least you'll have access to a wider selection of titles.

 

[WarthogARJ]

Aha!!!!
OK, there's an EXCELLENT forum, with GREAT links:
eGPU made simple

Feedback:
(1) Graphics Co-Processor:
The Graphics Co-Processor issue is a red herring.
Other people on Reddit/eGPU had asked exactly the same question, and the general reply was a bit vague.
But nobody had actually found any evidence of one, despite it being mentioned on the Amazon summaries of the specs.

However, there's a link to an actual teardown of a Sonnet eGPU, and there is definitely ZERO Graphics Co-Processor on it.
SONNET BREAKAWAY BOX REVIEW – IT’S COOL TO BE QUIET

It adds a bit to the confusion though, since it the "specificatons" Table it lists a Vega 64 as an "included GPU".
Which cannot be, since these Breakaway Boxes do NOT actually INCLUDE a GPU.
You buy it separately, or else as a special bundle.

They sell another product with the GPU as an integral part.

And I think the confusion comes in because for some Mac products you are severely limited in what GPU the OSx will recognise (without some work on your part).
And in both cases, the Radeon Vega 64, and FirePro 2270 are Apple OEM type GPU's.

In any case, if you look at main board photos, you can see that there is definitely NOT a Co-Processor.
At least nothing as big as a Vega 64 chip is.

And it does tell you the general design of a lot of eGPU's.
They have two parts to the main board for handling the input/output:
(1) THUNDERBOLT 3 CONTROLLER INTEL JHL 6540
(2) USB C CONTROLLER TI83

Then there's sometimes a SATA and Ethernet section.

(2) External eGPU Speed vs Internal:
There are specific benchmarks given, but in general you might see a 20% performance drop
But it depends on the monitor you use.
They say:
"In case of using Internal Monitor, CPU will send data to the eGPU for graphic processing and then eGPU will send processed data again to the laptop to display it on the Internal Display. In this case Thunderbolt bandwidth will be used in two ways and this will waste bandwidth and cause performance drop compared to using External Monitor. By Using External Display (Monitor) CPU will send data to eGPU for processing and then eGPU will forward processed data directly to the External Display (Monitor)"

(3) Measured eGPU Host-To-Device bandwith:
They've got a very interesting table that's woth looking over for those interested.
BEST EXTERNAL GRAPHICS CARD BUILDS

Read Sonnet's overview:

eGPU Breakaway Box 750/750ex - Sonnet

Thunderbolt eGPU enclosure for AMD and NVIDIA GPU cards and demanding PCIe cards. 750ex model includes USB 3.2 Gen 1 Type A ports and Gigabit Ethernet port.

www.sonnettech.com

which summarizes the primary reasons for considering an eGPU. If you don't do any of those things (you have never specified your actual usage case), forget the eGPU.

Your 27" iMac 5K 2019 already has a fairly capable video card so you'd have to stick a Radeon RX 5700 XT or RX 6800 XT to gain significant improvement.

No one sane would buy an eGPU+graphics card combo primarily for gaming on a desktop Mac. Any boost in gaming performance is a bonus but it's not cost effective to shell out all that cash because gaming is the primary goal. Just buy a console (Xbox, Playstation) and game on that: at least you'll have access to a wider selection of titles.

Thanks: good reply.

The iMac 2019 is a multi-purpose machine: and I bought it for a good price.
I have an old Mid 2012 MacBook Pro laptop, as well as a Mac Pro 2012 with 2 x Xeon I'm messing with.
And I've got a few assorted GPU's I could plug into an eGPU: I don't need to buy another for the eGPU if i do get one.

I got a Nvidia Tesla K80 sortof by accident in an auction.
Very cheaply.
It won't run happily on Mac, but booted into Win10 or Linux it it would be OK.
Unless I do a bit of panel-beating on the MacPro, I'd struggle to fit it in, along wth a standard GPU.
If I get into technical computing more heavily, I might use that in Linux or Win 10 in the iMac (booted natively into them).

I'm not a gamer, at least not now.
So yeah, buying an Xbox etc sounds like good dvice if i do get into it.

I think the only reason I'd get an eGPU is to mess around with it
The iMac is my most modern Intel system, and likely to remain that way for quite a while.
But I see it as ore of a laptop without a battery.....if you know what I mean.

But my main purpose of this exercise was to see if it made sense to get a Mac Intel based system with a more powerful GPU.
And yes, as you say, probably not with the iMac.
As it is, without the eGPU, it's a pretty good all-round machine.

 

[cvaldes]

I think the only reason I'd get an eGPU is to mess around with it.

I see.

Apple has a support page that lists recommended graphics cards and eGPU enclosures. You'll find the support document with an Internet search engine.

Relative to Macs, the main usage case for an eGPU is to provide better graphics processing power to Macs with integrated graphics like my Mac mini 2018 (Intel Core i7 with integrated HD 630 graphics) for applications like DaVinci Resolve.

If you just want to muck around with hardware without a specific goal you are free to do so.