eGPU Advantages for Davinci Resolve in 2020?

[Grumply]

Hi guys,

I'm pondering an upgrade to an "enthusiast" class Mac for work in Davinci at the moment (due to the extremely high costs of the Mac Pro 7,1) and I have a few questions about the benefits (specifically for Resolve) posed by eGPUs at this stage of the game (August 2020).

The inability to reasonably upgrade RAM in an iMac Pro at a sensible price rules it out for me (the cost would end up equivalent to a Mac Pro), so the two options I'm considering are:

- 2020 16" Macbook Pro (2.4Ghz 8-core i9, 64GB RAM, 5600M 8GB GPU)
- 2020 27" iMac (3.6Ghz 10-core i9, 128GB RAM, 16GB 5700 XT GPU)

Now the various eGPU tests and benchmarks from the past few years that I've pored over, have presented a whole range of issues, many of which have now been addressed (driver optimisations/general compatibilities etc.) and with the genuinely powerful internal GPUs found in these two models, it appears that for a lot processing situations, the bandwidth limitations of TB3 will actually slow down performance when you incorporate an eGPU, rather than speed things up.

So what I'm hoping to clear up, is the specific situations in which Davinci CAN take advantage of having eGPUs plugged in.

Now I have a pair of Radeon VIIs currently, so for the sake of the hypothetical (assuming they're actually going to be useful in this scenario) those are the two eGPUs I'd be connecting to the new computer.

So the questions I'm hoping to answer are:

1) Will eGPUs speed up realtime playback within the timeline as I grade/edit things?
2) Will eGPUs speed up debayering/decompression of raw files?
3) Will eGPUs improve the speed at which the cache is rendered?
4) Will eGPUs improve export times?
5) The 16" MBP has two TB3 controllers, will plugging one eGPU into each side yield a performance advantage?
6) The 27" iMac only has a single TB3 controller, will that halve the performance of the two eGPUs compared to the MBP?

Any insight anyone could provide would be much appreciated.

Cheers

 

[skilar]

This question is a couple weeks old, so you may have found an answer. But just in case...

I'm running a 2016 MBP 13". Obviously this machine is much older and has far less power than either of the builds you're considering. With the integrated graphics I can't get realtime playback when grading even 1080p footage. Export times are....slow.

I have an RX 580 in a Razer Core X. The card isn't anything special, but it makes things bearable. I get realtime playback on graded 4k files just fine. It also cuts my export times from 9.5 minutes to just under 3 minutes for a 3 minute long clip. That's applying a LUT, scaling from 4K to 2K, and converting from ProRes 422 HQ to ProRes Proxy.

So with that said, I think the internal card on either of those machines will be very capable. I think you'll get excellent realtime playback, even with 4K RAW. If you go above that, to 5.6K or 8K, I'm not sure. I'd imagine you'd see an improvement when connecting an eGPU, but not to the extent as if it were internal.

Bare Feats has some interesting benchmarks that show a distinct improvement in performance when using an eGPU with a 16" MBP.

 

[Grumply]

Thanks, really appreciate the info. Barefeats benchmarks are very helpful, however most of the Davinci Resolve benchmarks that people use, all involve noise reduction (which is hugely dependent on GPU performance), however what's not as clear, is the benefits of additional GPU power in situations that aren't specifically using noise reduction. Will you still get benefits from the additional processing power? Though from what you're describing, it sounds like you do, which is great.

 

[pldelisle]

Having an eGPU with such good internal GPU isn't worth all the trouble it will bring you.

 

[Grumply]

Having an eGPU with such good internal GPU isn't worth all the trouble it will bring you.

Why? What trouble will it bring?

 

[pldelisle]

Why? What trouble will it bring?

I read many times on this forum that eGPU support isn't quite there yet. My feeling is that it's a patch, not a real "production level" solution. App crashing, multi monitor support weird, limited bandwidth (thunderbolt 3 is still a fraction of a full x16 PCI-E 3.0 bus) and other weird things occurring when you have this setup make me vote against this solution.

With a 5700XT, I really doubt you could benefit from anything external.

 

[Grumply]

I read many times on this forum that eGPU support isn't quite there yet. My feeling is that it's a patch, not a real "production level" solution. App crashing, multi monitor support weird, limited bandwidth (thunderbolt 3 is still a fraction of a full x16 PCI-E 3.0 bus) and other weird things occurring when you have this setup make me vote against this solution.

With a 5700XT, I really doubt you could benefit from anything external.

I used to assume several of the same points, but actually, for computing workloads, the performance difference between running a GPU in a x16 slot vs a x4 slot actually appears to be quite tiny.

And most of the instability issues reported when eGPUs were very new tech, appear to have (recently) been largely ironed-out (or at least greatly improved) through driver updates.

There are still a lot of questions that remain though (when integrating with machines that already have powerful GPUs onboard):

1) Will eGPUs speed up realtime playback within the timeline as I grade/edit things?
2) Will eGPUs speed up debayering/decompression of raw files?
3) Will eGPUs improve the speed at which the cache is rendered?
4) Will eGPUs improve export times?
5) The 16" MBP has two TB3 controllers, will plugging one eGPU into each side yield a performance advantage?
6) The 27" iMac only has a single TB3 controller, will that halve the performance of the two eGPUs compared to the MBP?

 

[thermalthrottle]

I'm in a similar situation to the OP, currently using an old quad core i7 mac and looking to upgrade to either of the 2 iMac 2020 configs with an 5700xt. Also new to the eGPU scene and have been fortunate to be able to run a 2019 16inch MBP i9 5500m 8GB as a loaner to get me by as well as a Lenovo laptop with 9th gen i7 rtx 2060. My egpu is a 2070 super which I have paired with both the 2019 MBP and the windows laptop and the results have been surprising.

In Mac OS I can't use the 2070super but have used an old rx 580 and performance was around about the same as the 5500m for Final Cut Pro even though the 580 should perform a lot better then the 5500m. I suspect this is more to do with eGPU optimisation rather then the thunderbolt 3 port being a bottle neck as I was mostly working on 1080 with the occasional 4k footage. Now if I was working on 6k or even 8k then I reckon the thunderbolt 3 protocol would be much more of an issue. According to activity monitor the egpu 580 rarely hit above 50% utilisation whereas the 5500m was maxed out many times.

On the windows side, I have to run some software that requires Nvidia cards to render and the experience with running the MBP 2019 i9 in bootcamp has been fairly smooth and performs more reliably then the lenovo i7 laptop 90% of the time. The Lenovo has a habit of going to sleep if it's been rendering for too long due to overheating which I have only experienced twice with the MBP 2019 i9. However, having said that, the thermal throttling on the 2019 MBP is insane and affects the speed with which it can render things. To make matters worse, when either laptop is rendering with the egpu and goes too hibernate due to overheating then the results are a disaster as there appears to be some kind of issue with windows waking up properly while connected to egpu and many times I have had to shut down and lose hours of rendered work.

As an example of the 2019 MBP thermal throttling, running neat video plugin on final cut pro on a 720p pro res timeline results in the 2.4ghz cpu running at 1.5-1.6ghz when throttling. My old quad core i7 stays consistently around base clock of 2.3 so it's actually not that much slower despite having half the amount of cores. Also according to Neatbench, the 2019 MBP i9 5500m can only render at 17 fps on a 1080p timeline while the Lenovo i7 RTX 2060 does 26 FPS just on gpu only.

What's interesting however is that the egpu 2070 super card which should run rings around the mobile 2060 can only achieve 15fps! This was pretty consistent with both the 2019MBP in bootcamp as well as the Lenovo.

Now OP is looking at a MBP with the 5600m GPU which should perform a lot better then the 5500m I was using, and I heard reports it should perform similarly to the RTX 2060 mobile chip. Likewise the 5700xt card is supposed to be in a similar ballpark to the RTX 2070. In which case the 5600m should outperform the 5700xt eGPU when rendering at high frame rate as the thunderbolt 3 might act as a bottle neck.

If on the other hand, the software you are using is rendering at a really slow rate like single digit FPS then I think the thunderbolt 3 connection will be less of a bottleneck. That's been my eperience using A.I software that renders at a really slow rate on the 2070 super, performing the same in an epgu enclosure as it does inside a pc tower with the same amount of cores as the laptops I've been using.

TL: DR - The MacBook Pro thermal throttles like crazy, the iMac may not. Thunderbolt 3 may be a bottle neck depending on the size of the video files i.e 6k/8k, and whether the software renders at a high or low frame per second. High FPS, thuderbolt 3 egpu probably won't perform as efficiently as the onboard 5600m or 5700xt due to bandwidth limits.

Also with Windows/bootcamp the egpu has sleep issues which could lose hours of work if laptop overheats and goes to hibernate then fails to wake up properly.

 

[0279317]

I used to assume several of the same points, but actually, for computing workloads, the performance difference between running a GPU in a x16 slot vs a x4 slot actually appears to be quite tiny.

And most of the instability issues reported when eGPUs were very new tech, appear to have (recently) been largely ironed-out (or at least greatly improved) through driver updates.

There are still a lot of questions that remain though (when integrating with machines that already have powerful GPUs onboard):

1) Will eGPUs speed up realtime playback within the timeline as I grade/edit things?
2) Will eGPUs speed up debayering/decompression of raw files?
3) Will eGPUs improve the speed at which the cache is rendered?
4) Will eGPUs improve export times?
5) The 16" MBP has two TB3 controllers, will plugging one eGPU into each side yield a performance advantage?
6) The 27" iMac only has a single TB3 controller, will that halve the performance of the two eGPUs compared to the MBP?

As you point out instability issues are now a non-issue, at least for me. I have a 5700XT which I use with my iMac Pro base model + 64 GB RAM. (I got the eGPU for other reasons but now use it with the iMac Pro) I do notice an improvement in rendering in FCPX. Have you gotten answers to your questions?

 

[thermalthrottle]

As you point out instability issues are now a non-issue, at least for me. I have a 5700XT which I use with my iMac Pro base model + 64 GB RAM. (I got the eGPU for other reasons but now use it with the iMac Pro) I do notice an improvement in rendering in FCPX. Have you gotten answers to your questions?

I used an iMac pro with an nvidia egpu in bootcamp for work, the iMac pro had start up issues recognising the epgu but once it was working it would stay on and worked flawlessly for several days without issues. An iMac 2020 I borrowed to do the same thing did go to sleep several hours into a render and failed to wake up properly thus losing hours of work, in just the same way the MacBook pro 16 inch would. I chalk this up to a thermal issue hence why the better cooled xeon iMac pro worked like a champ.

 

[Grumply]

As you point out instability issues are now a non-issue, at least for me. I have a 5700XT which I use with my iMac Pro base model + 64 GB RAM. (I got the eGPU for other reasons but now use it with the iMac Pro) I do notice an improvement in rendering in FCPX. Have you gotten answers to your questions?

No, I was never able to get any clear answers to my questions.

Ended up finding the extra cash to stretch to a 7,1 Mac Pro - which as painful as the cost was, instantly made it clear to me that there was never really a viable alternative in adding expansion boxes to an iMac or iMac Pro. I needed a tower (there's just too much crap I had to stuff into the machine to get a viable build for the work I do - Colour Grading).

 

[0279317]

No, I was never able to get any clear answers to my questions.

Ended up finding the extra cash to stretch to a 7,1 Mac Pro - which as painful as the cost was, instantly made it clear to me that there was never really a viable alternative in adding expansion boxes to an iMac or iMac Pro. I needed a tower (there's just too much crap I had to stuff into the machine to get a viable build for the work I do - Colour Grading).

I'm constantly searching for answers (to questions) that would seem answerable yet the waters are always murky. I guess it's the nature of the beast. More than once I've mis-purchased or over-purchased to try and ensure a working solution. For me the latest concerns are audio interface issues. Good luck.