eGPU success - iMac "GPU memory full" solved

[Ruben de Boer]

Hi folks,

There are a number of stories here about people wanting to try an external GPU solution, but I haven't seen a story of someone who actually included it in their workflow. I took the chance and here's my report...

What I have: a late 2013 27" iMac with a GTX 775m 2gb GPU and 32gb of RAM (yes, this is a Thunderbolt 1 machine). 1080p or 4K editing is just fine on this machine, but adding even just one NR node, a power window, a LUT and some basic color correction really slowed it down, up to the point where files wouldn't play back at all (or just 0,001fps). Even with proxies DaVinci Resolve couldn't keep up when changing some parameters and would occasionally crash or give me a GPU memory full message (and then the UI started to glitch and would eventually crash my whole system after a while).

What I did: I bought a secondhand Akitio Thunder2 PCIe enclosure (cost me € 75), made a hole in the side for air ventilation (cost me 2 hours of cutting and filing), a DELL DA-2 power supply (€ 15) and a Zotac GTX 1060 6GB GPU (€ 225). There is just one software patch to install (from egpu.io, which install the correct drivers and all) and everything worked right away. DaVinci Resolve recognizes the card as a second GPU and uses it for compute, my GTX 775m is used for the UI. I'm probably using only 25% of the full speed improvement of the 1060 GPU because of the Thunderbolt 1 bottleneck, but it's still much faster than it used to be with only the internal card, and that's what counts!

Result: even the most difficult scenes with around 12 nodes (including NR on 3 channels, added 16mm grain, tracking windows, a LUT, et cetera) it plays at 10fps. Other scenes with just NR would play back either real time or around 15fps (depending on the resolution). Most of the times it would quickly cache the files when playing back, so a second time around it played back fine.

Let me know if any of you need advice with setting up a eGPU!

[rick.lang]

Impressive difference, good job, Ruben!

[cassiusthedirector]

Really good to know, thanks Ruben!

[digitalinnovations]

I would love some more info on this setup for my iMac...such as what is currently the best / most powerful graphics card you can put in?

[Timothy Cook]

I would love some more info on this setup for my iMac...such as what is currently the best / most powerful graphics card you can put in?

You may want to give it a couple of months. eGPUs for Mac aren't officially ready yet and only developers have the option to run them with "Native built for eGPU" Apple software. Apple is opening it's OS for eGPUs but not officially (meaning ready for public use) until spring.

As of right now you can run eGPUs with Macs and NOT be in the developer program, by using the eGPU community's hack, but there are several work arounds and it doesn't maximize the cards you use with it, unless you use Boot Camp and it's still fairly buggy at times.

[Ruben de Boer]

I would love some more info on this setup for my iMac...such as what is currently the best / most powerful graphics card you can put in?

eGPU.io is a wonderful source for all kinds of info. They have a list of combinations (computer / enclosure / GPU card) with some additional info of how each on is build.