Twinmotion, iMac + external GPU upgrade

[Robert Nichols]

I read an article a few months ago discussing the use of an external GPU to enable an otherwise underpowered computer to run Twinmotion properly. The external GPU was rigged up in a Thunderbolt expansion enclosure the had its own power supply.

This solution sounds great to me. We've found that the top level 27" iMac (regular vanilla iMac, not the iMac Pro) provides great value and longevity for about 90% of our ArchiCAD needs. We are still happily running late-2013 iMacs on 4 of our workstations. But, this machine is not fit for the graphic demands of Twinmotion or similar. An external solution would isolate the cost of the upgrade (i.e., wouldn't need to upgrade an entire workstation to iMac Pro), and would let the solution move between workstations as needed.

Does anyone have experience with such a setup? Video card recommendations? Expansion box recommendations? We're Mac based office.

Thanks, all!

[Robert Nichols]

I see Twinmotion support site recommends "AMD Radeon Vega series card or higher". I'm really not familiar with this hardware segment. Macsales.com has Radeon Pro W5700 for US$ 830. I'm not certain that meets the "Vega series card or higher", requirement, but it sure seems like plenty of money to throw at the problem!

[Karl Ottenstein]

I'm moving this into the Hardware forum, as it is not an ARCHICAD question...

You'll want to search for "eGPU". Your old 2013 iMacs have only Thunderbolt 2 and lower specs than current machines which may be limiting. Also, just because an eGPU box lets you plug in a graphics adapter... it still must be an adapter that your version of MacOS supports natively.

The Apple web site store itself sells two eGPU's - Blackmagic and Sonnet:
https://www.apple.com/search/eGPU?src=alp

But both require the faster Thunderbolt 3 port which your old iMacs lack. OWC/Macsales.com has more TB 3 options.

You may find a Thunderbolt 2 box, but I think that would be a waste of money vs getting current hardware. For the price of a new iMac and an eGPU, you could probably get an iMac Pro.

[Robert Nichols]

Thanks, Karl. I made my post confusing. We have newer iMac's in the studio, and I would probably get another new one for this purpose if I go ahead with external GPU. I mentioned our late-2013's just to make a point about the longevity of those machines for use as a basic ArchiCAD workstation. It's almost never the case that more than 2 people are rendering or otherwise working on graphics intensive tasks at the same time.

[Karl Ottenstein]

Aha. Gotcha, Robert. Yes, then I would definitely look at one of the Thunderbolt 3 eGPU boxes with a Catalina-supported card. The eGPU can also be used with any of your newer iMacs as well as any MacBook Pro with TB3 ports as well, giving you flexibility to work on whichever machine needs it at the time.

Cheers,.
Karl

[Karl Ottenstein]

Just noticed an article from 10 days ago giving benchmark results for a TB3 eGPU with the new MBP 13". The choice of card - vs a much more expensive card - and the results vs the adapter in the MBP 16" might be of interest.

Note the CAUTION paragraph - which may (or may not?) apply to attaching an eGPU to an iMac...

https://barefeats.com/macbook-pro-13-inch-2020-egpu-boost.html

[Lingwisyer]

Depending on how urgent it is, AMD's and NVIDIA's new cards are apparently expected to be released Q4 so prices of current cards may fall as that approaches. You could also consider holding out and getting the new cards.



Ling.