iMac Pro eGPU Questions

[SecuritySteve]

So I discovered I actually do qualify for some form of stimulus check, and should be receiving those funds shortly. I spend a lot of time gaming as a hobby on the side (maybe too much), and I'd like to see if I can get better performance by offloading graphics (for the internal display) to an eGPU. According to this support page ...

Use an external graphics processor with your Mac - Apple Support

Learn how to access additional graphics performance by connecting to an external graphics processor.

support.apple.com

... any supported Metal game can accelerate itself with an eGPU on the internal display. Since my primary game is World of Warcraft, I checked the forums and Mac users have reported that it works really well in this fashion, and since you offload the thermal pressure from the internal GPU to the eGPU, the CPU has more thermal headroom and performs better too.

I've picked this GPU and this eGPU tentatively before I pull the trigger...

Sonnet eGFX Breakaway Box 650 - Thunderbolt 3 to eGPU PCIe Card Expansion System

Sonnet eGFX Breakaway Box 650 - Thunderbolt 3 to eGPU PCIe Card Expansion System

www.amazon.com

XFX RX 5700 Xt Thicc III Ultra 8GB Boost Up to 2025MHz GDDR6 3xDP HDMI Graphics Card (Rx-57XT8TBD8)

Introducing the new XFX thicc III ultra 5700 XT. Built with style and dynamic cooling power in mind to yield lower temperatures and heightened performance that adapt to the intensity of the moment.

www.amazon.com

Main reason is that the Sonnet eGFX breakaway box is heavily supported by Apple, and it's not made by Razer (which I have a loathing of the quality of their products after years of use and lack of Mac support). As far as I can tell, this is the best AMD GPU for gaming. I'd like to be proven wrong by anyone here.

My Questions

Anyone already running a similar setup on their iMac on Windows for Windows games? I'd really like to know as I'd like to give DOOM Eternal a try too.

Anyone know of a better AMD GPU for gaming? Anything else I find is either a lower clocked version of that 5700 XT or more catered around rendering.

 

[lilcosco08]

That card won't fit.

This one will but it'll be a tight fit

Core X can probably fit either

 

[SecuritySteve]

That card won't fit.

This one will but it'll be a tight fit

Core X can probably fit either

Can you post where you found it won't fit? The sonnet one claims to fit "One full-length, full-height, double-width PCIe card" and the measurements seem to fit.

 

[SecuritySteve]

Found it here http://www.sonnettech.com/support/kb/kb.php?cat=524&expand=_a2_b914&action=b991#b991


... ugh I hate Razer so much though. Obviously I want the best card I can get that will work. Luckily that card you linked looks almost as good, but is a bit pricier.

 

[lilcosco08]

@SecuritySteve on the Amazon page for the Sonnet, it says it supports cards up to 312mm (12.28"), the Thicc III is 12.4" long (lives up to its name)

This one clocks in at 280mm

 

[bdbolin]

I love my sonnet. I have a 580 in it I believe. It's probably the only hardware that's flawlessly worked on my mac mini.

 

[SecuritySteve]

Yeah I'm looking for cards around 2015-2035 boost clock speed and 1800+ core clock speeds. This means it's an OC'd card with beefy cooling solutions on it, which is why I'm struggling to fit it into the sonnet. I could go with something else, but the sonnet has such a good reputation for flawlessly working that I'd rather stick with it and go with a slightly different card.

Also still looking for Windows performance folks. I've done my research about error 12 and it looks nasty ... however that was from a long time ago and perhaps Windows updates have fixed it by now?

 

[SecuritySteve]

Open Box: PowerColor RED DEVIL Radeon RX 5700 XT Video Card AXRX 5700 XT 8GBD6-3DHE/OC - Newegg.com

Buy Open Box: PowerColor RED DEVIL Radeon RX 5700 XT 8GB GDDR6 PCI Express 4.0 CrossFireX Support ATX Video Card AXRX 5700 XT 8GBD6-3DHE/OC with fast shipping and top-rated customer service. Once you know, you Newegg!

www.newegg.com

We might have a winner...

 

[lilcosco08]

I think you're better off waiting, RDNA2 is coming sometime this year (hopefully with the new iMac Pro) and the 5700xt is only ~20% better than Vega 64, though the 5700xt would probably help a lot with thermal throttling, as you said. Also, prices are inflated right now due to covid.

If you dont care about OS X compatibility, Ampere is also coming soon so you could get a 3080ti or 3080 that would destroy the 5700xt (or a 2080ti for that matter) https://www.pcgamesn.com/nvidia/rtx-3080-ti-ampere-details-leak

 

[SecuritySteve]

I think you're better off waiting, RDNA2 is coming sometime this year (hopefully with the new iMac Pro) and the 5700xt is only ~20% better than Vega 64, though the 5700xt would probably help a lot with thermal throttling, as you said. Also, prices are inflated right now due to covid.

If you dont care about OS X compatibility, Ampere is also coming soon so you could get a 3080ti or 3080 that would destroy the 5700xt (or a 2080ti for that matter) https://www.pcgamesn.com/nvidia/rtx-3080-ti-ampere-details-leak

I had not heard about RDNA2, so that might give me pause. I do care about OS X compatibility, so until NVIDIA and Apple start playing nice, I'll stick with red team.

 

[SecuritySteve]

Decided to go with this card...

https://www.sapphiretech.com/en/consumer/nitro-radeon-rx-5700-xt-se-8g-gddr6

And the 650W Sonnet enclosure. Hopefully I will have it all here by next week to do some benchmark posting.

Edit: Why not wait?

A: Because RDNA2 may be pushed out into 2021 because of COVID. I'm not going to wait that long, and even if it does come out on schedule, the card will likely be of the more expensive variety. I'll wait for RDNA3.

 

[mmomega]

I have 3 eGPU's, a Vega 56Strix, Vega64 watercooled and a Radeon VII.
My iMac Pro built in Vega64 is quicker than any of the eGPU's in pretty much all scenarios.

Now if you want to throw dollar bills at a very tiny scenario where the eGPU may shine, then that is another thing all together.
A decent eGPU box is roughly $300, whether it is a cheap box and then you upgrade to a decent power supply or just buy one with a 600-650w PSU right away.
Then however much the video card is.

I have been doing eGPU's on iMacs, Mac Minis, trash can Mac Pro since I started with the 980Ti and a hacked together Thunderbolt 2 PCIE box and external PSU.

For a Mac Mini, it makes some sense.
For a MacBook Pro / desktop replacement, it makes some sense.
For the old Mac Pro, it made some sense.

For an iMac Pro or 2019 iMac. To me it makes financially zero sense to performance gain. And I have 3 of these, just because.
And it is not because it gives a performance advantage.

Even just over time, GeekBench 5 and 4 GPU Compute scores across various machines.

mmomega's Profile - Geekbench

But this is ONLY my opinion.

 

[SecuritySteve]

So I finally got everything set up, and got to test in macOS and Windows on various games.

Because this card is heavily overclocked, it's performance matches the Vega 64 in my iMac Pro in almost every situation, but gives me the additional thermal headroom without my iMac Pro sounding like a leaf blower to get decent performance. I am very happy with the enclosure, despite the tight GPU fit.

The only situations where the performance does not match, is in older game engines that are not optimized or configured for eGPU usage. On those games performance tanks as low as half of the Vega 64. As time goes on, this situation will be less and less common. I expect that this enclosure will be my graphics upgrade avenue again in 3-4 years.