Can the MBP's GPU and eGPU work at the same time?

[smirking]

I'm entirely clueless when it comes to eGPUs so I'm hoping someone can help me with a very basic question. I'm thinking of getting the ne Blackmagic eGPU for photography. I like to run Capture One Pro on two screens with my editing window on my LG 5K Ultrafine and a catalog browser on my 2016 MBP's screen. Capture One Pro runs ok when limited to just one window off of my 2016 MBP, but when I try to drive two windows, it drags.

If I get the Blackmagic eGPU and plug my LG 5K Ultrafine into it directly, am I going to get the benefit of both GPUs or does my MBP's GPU defer to the more powerful eGPU? If both can be active at the same time, how do they divide up tasks? Do they both handle some processing? Does the mobile GPU kick in only when the eGPU is saturated? Or does the eGPU only accelerate my external monitor while my internal GPU drives the MBP screen?

 

[Tapiture]

It's a good question that you might want to take to a more technical forum like Tom's Hardware or Stack Overflow.
I took this from Reddit member Dippyskoodlez:

This answer is actually a little complicated because it depends on the specific GPU implementation inside of the laptop as well as lane configuration.

Configurations are different between Macbooks, a device utilizing Optimus or not (Nvidia based) and a device using AMD switching tech or a custom design. I’m not familiar enough to make a statement re: AMD implementations, but I have seen the topology for optimus.

I’ll use my XPS 15 9560 as an example. It is an optimus device utilizing a 1050, HD650 and a TB3 port (2 lane through chipset).

In normal operation the HD650 renders to the internal display at all times. When a 3d application begins to be accelerated using the 1050, the 1050 GPU renders the frame and copys this to the framebuffer of the HD650. This can be monitored simply by looking at the different GPU utilization in GPU-Z. This is the primary method “Optimus” utilizes to hot standby a dGPU.

This has a few interesting quirks, as both GPUs are actually accessible with a little trickery, but causes a HUGE performance hit if the HD650 has to modify the frame before outputting it. (i.e. Minecraft would go from playable to 5-20fps)

When an eGPU(Nvidia) is added, anything going to the internal display is handled by the HD650, and any external displays connected to the eGPU are handled by the eGPU. The GTX 1050 is still able to do tasks, but due to it’s reliance on the HD650 it cannot do anything except send the frame to anything but it’s framebuffer.

The 1050 works great as a CUDA device in addition to an eGPU.

In a Macbook, this gets a but more complicated depending on if you’re using Windows or Mac OS, I haven’t used an eGPU with that implementation since TB3 has come out but it had a lot of interesting quirks when it first started being possible to do. I would imagine the later Mac OS eGPU support has changed it’s behavior quite a bit since I last used it re: internal display.

Re: Strong internal GPU for laptop selection, I would base this on if you actually want GPU power on the go. eGPUs are not insanely portable physically, and considering the significant internal screen acceleration performance hit encountered if you travel without a monitor, viability is of questionable value.

CPU speed is still critical, but a dGPU is preference. Device selection is still very limited today if you want to strictly avoid a dGPU though, as many systems with something like a 7700HQ will also have a 1050/1060 anyways.

 

[smirking]

It's a good question that you might want to take to a more technical forum like Tom's Hardware or Stack Overflow.

Thanks for posting that. Were you looking into the same issues? That's more complicated than I expected. The answer sounds like it could be any of the above or all of the above depending on the particular setup, but I am getting the sense that using an eGPU to directly drive an external monitor has significant performance benefits regardless of how the silicon in the two GPUs are being allocated.

You got any thoughts on the lifespan of an eGPU enclosure?
https://forums.macrumors.com/threads/is-upgradeability-in-an-egpu-really-that-important.2129794/

 

[Tapiture]

Thanks for posting that. Were you looking into the same issues? That's more complicated than I expected. The answer sounds like it could be any of the above or all of the above depending on the particular setup, but I am getting the sense that using an eGPU to directly drive an external monitor has significant performance benefits regardless of how the silicon in the two GPUs are being allocated.

You got any thoughts on the lifespan of an eGPU enclosure?
https://forums.macrumors.com/threads/is-upgradeability-in-an-egpu-really-that-important.2129794/

Like I said, you should ask on Tom's Hardware. I, nor most other people on these forums, are qualified to give answers on that because it is very technical and when you're buying such expensive equipment I don't want to provide false information. The reddit answer was a response to the question "Does an eGPU override the GPU in a laptop, or do the two work together?" Here's a link to that page: https://www.reddit.com/r/eGPU/comments/86xu6d/does_an_egpu_override_the_gpu_in_a_laptop_or_do/

 

[craig1410]

I'm really interested to see how this works out too as I ave just ordered a Blackmagic eGPU and should have it tomorrow. I have a 2016 MBP (15", 2.7GHz i7, 16GB, 1TB, 460 GPU) and also have two LG Ultrafine 5K displays which I bought when they were heavily discounted. The MBP "can" run both displays simultaneously but it tends to spin up the fans a lot due to the GPU load of pushing all those pixels. In fact I run the laptop display as well as both 5K displays and it's pretty amazing that it can do it at all but it's not a great experience to be honest. Running just one 5K display however, is perfectly acceptable and seems pretty smooth.

So, what I'm hoping is that, when I connect the eGPU, it will drive the primary 5K display leaving the onboard Radeon Pro 460 to drive the secondary 5K display and probably the onboard display. That would seem to me to be the most logical way for things to work otherwise the eGPU would be driving one display directly and another display indirectly which can't be ideal in terms of traffic on the TB3 connection. Having both the dGPU and eGPU running together would also boost the overall GPU capability of the system.

I'm pretty sure I remember an Apple presentation (maybe WWDC keynote?) where they showed Final Cut or some other app processing video using two eGPUs and I remember it showed green lines on the screen where each GPU was processing a proportion of the frame. As I recall, there were 3 sections - two were the same size and were processed by the two eGPUs and the third section was much smaller since it was being processed by the onboard GPU. It seemed smart enough to split up the frame according to the power of each GPU involved.

Now, whether that also works when rendering the desktop and doing general app tasks I don't know. This might have just been a specific optimisation in Final Cut.

Anyway, if there isn't already a thread for "Blackmagic eGPU - first impressions) or similar then I might start one once I receive my order.

 

[smirking]

I'm pretty sure I remember an Apple presentation (maybe WWDC keynote?) where they showed Final Cut

If you want to power Final Cut, you may want to wait. Final Cut isn't supported by the BlackMagic yet. There's a workaround, but I think the issue is that it won't drive your 5K directly. It'll act like an ordinary eGPU and by that I think it won't apply its resources specifically to pushing pixels through the 5K. that would remove the biggest selling point of the BlackMagic as the only eGPU on the market capable of powering the Ultrafine 5Ks directly.

I'm planning on getting one of these myself next week when they become available again around here. I don't need top of the line specs. I'm mostly using it to speed up my photography workflow and also make my 2016 MBP run better when I have my 5K plugged in.

I'm only running one 5K and I do notice a performance drag if I'm also using my laptop screen at the same time. I can't imagine trying to drive two 5K's at the same time when I can't even drive a 5K plus my laptop screen without some lag. I use Capture One Pro for my photography and when I try to have a photo browser on my laptop and the main viewing window on my 5K, it is S-L-O-W!

 

[craig1410]

If you want to power Final Cut, you may want to wait. Final Cut isn't supported by the BlackMagic yet. There's a workaround, but I think the issue is that it won't drive your 5K directly. It'll act like an ordinary eGPU and by that I think it won't apply its resources specifically to pushing pixels through the 5K. that would remove the biggest selling point of the BlackMagic as the only eGPU on the market capable of powering the Ultrafine 5Ks directly.

I'm planning on getting one of these myself next week when they become available again around here. I don't need top of the line specs. I'm mostly using it to speed up my photography workflow and also make my 2016 MBP run better when I have my 5K plugged in.

I'm only running one 5K and I do notice a performance drag if I'm also using my laptop screen at the same time. I can't imagine trying to drive two 5K's at the same time when I can't even drive a 5K plus my laptop screen without some lag. I use Capture One Pro for my photography and when I try to have a photo browser on my laptop and the main viewing window on my 5K, it is S-L-O-W!

No, I’m not a Final Cut user, I’m a web developer and quite honestly I don’t really need a lot of GPU resources in general terms but I do benefit greatly from a lot of pixels across which to spread my work. When I bought my MBP I maxed out the GPU because I intended to buy the 5K display and knew it would need all the GPU resource it could get. Then I had the crazy idea of buying two displays because Phil Schiller said it could drive them both, plus the onboard display! To be fair to Phil, it can indeed drive all those pixels but it places a lot of strain on the themal system and the resulting fan noise is a bit tiresome.

So, what I’m hoping is that by adding the eGPU, I can remove the thermal load from the dGPU and give the CPU all the cooling it might need to stay in turbo mode more often and/or keep the fan noise to a minimum. That might even tempt me to finally sell my 2014 iMac 5K and migrate to the MBP + eGPU + LG 5K (x2) lifestyle!

Given the patchy Intel CPU year on year improvements I figure spending £599 on an eGPU will delay my need to upgrade my MBP until we either have a decent Intel update or Apple switch to ARM CPUs for the Macs. Let’s see...

 

[rafark]

you might want to take to a more technical forum like Stack Overflow.

Please don't. He'll get downvoted to hell. Stack Overflow is for programmers, not end users.

 

[smirking]

No, I’m not a Final Cut user, I’m a web developer

LOL, no wonder I keep bumping into you in here. Everything you just said more or less describes me too. I'm a Web developer as well. I have certain things I'd like to do with two displays (one 5K one laptop) and I find that it ends up causing thermal load that slows everything else down so I usually just stick to one screen. Besides wanting the GPU, I'd also find having a proper hub for additional ports to be a bonus. I can declutter the area behind my monitor a little bit.
[doublepost=1533944324][/doublepost]

Please don't. He'll get downvoted to hell. Stack Overflow is for programmers, not end users.

LOL, well... I happen to be one of those. This doesn't sound like a Stack Overflow question though.

 

[Tapiture]

LOL, no wonder I keep bumping into you in here. Everything you just said more or less describes me too. I'm a Web developer as well. I have certain things I'd like to do with two displays (one 5K one laptop) and I find that it ends up causing thermal load that slows everything else down so I usually just stick to one screen. Besides wanting the GPU, I'd also find having a proper hub for additional ports to be a bonus. I can declutter the area behind my monitor a little bit.
[doublepost=1533944324][/doublepost]

LOL, well... I happen to be one of those. This doesn't sound like a Stack Overflow question though.

Please don't. He'll get downvoted to hell. Stack Overflow is for programmers, not end users.

I don’t often use Stack Overflow, but I also mentioned Tom’s Hardware which I do use and I’ve found the people on there to be very friendly and helpful.

 

[craig1410]

Please don't. He'll get downvoted to hell. Stack Overflow is for programmers, not end users.

Why does this make me feel like a character in Tron: The Legacy? “I fight for the users!”

I feel like breaking out a Venn diagram showing the Programmers ARE ALSO end users!

LOL, no wonder I keep bumping into you in here. Everything you just said more or less describes me too. I'm a Web developer as well. I have certain things I'd like to do with two displays (one 5K one laptop) and I find that it ends up causing thermal load that slows everything else down so I usually just stick to one screen. Besides wanting the GPU, I'd also find having a proper hub for additional ports to be a bonus. I can declutter the area behind my monitor a little bit.

Haha, yeah I really like the way the LG 5K can extend the stand height to rise above the MBP display. That’s a really nice arrangement. In that configuration I like to use the MBP display for Terminal use and the LG display for my dev tools and web browser. Even better, with two 5K displays I can have the dev tools and web browser on separate screens which allows faster dev iteration. It’s indulgent I know, but fantastic until the fans start screaming!!!

My eGPU is en route and should be here in 12 hours so I’ll let you know how I get on. I have guests visiting this weekend so I might need to sneak in some analysis when they’ve gone to bed! Shhhhh!

 

[rafark]

I don’t often use Stack Overflow, but I also mentioned Tom’s Hardware which I do use and I’ve found the people on there to be very friendly and helpful.

Why does this make me feel like a character in Tron: The Legacy? “I fight for the users!”

I feel like breaking out a Venn diagram showing the Programmers ARE ALSO end users!

Lol I hate with a passion being that guy, I really do!. I personally don't care for their rules. My post was just a warning to the OP, since people over there can be quite unfriendly and over-reacting when it comes to breaking the rules.

 

[Tapiture]

Lol I hate with a passion being that guy, I really do!. I personally don't care for their rules. My post was just a warning to the OP, since people over there can be quite unfriendly and over-reacting when it comes to breaking the rules.

I’ll agree with you there. The people on Stack Overflow can be.... unforgiving...

 

[craig1410]

Well, first impressions are encouraging...

I can confirm that the eGPU seems to work concurrently with the onboard Radeon Pro 460 dGPU when driving multiple LG 5K displays.

To test this I used the Activity Monitor app to graph the GPU history (Cmd-4) and then simply dragged a Safari browser window rapidly around each display. This causes a measurable load to appear on the activity monitor GPU graphs. If I do this for the display attached to the eGPU, the load appears on the eGPU and vice versa for the LG display attached directly to the MBP. For the MBP's own LCD it also appears to be driven by the Radeon Pro 460 dGPU with the Intel integrated GPU sitting idle. This is all unsurprising in many ways but there was a possibility that the eGPU would also take precedence over the 460 dGPU because as I understand it, it's possible for an eGPU to accelerate a display that is not directly connected to the eGPU.

So, in simple terms, this means that the GPU performance of my MBP is now equal to the sum of the Radeon Pro 580 and the Radeon Pro 460! I realise this will vary by app but my main aim was to give my MBP the GPU power needed to drive 2 LG 5K displays plus onboard LCD without spinning up the MBP fans. It definitely seems to achieve that goal. So according to Geekbench 4, my eGPU has an OpenCL compute score of 110,212 and the 460 dGPU is 55,132 so that's 165,344 in total which is higher than the Vega 56 in the iMac Pro. Before anyone says it, I totally understand this doesn't make my MBP an iMac Pro beater...

Anyway, so far so good. Now to try running some games...

 

[smirking]

Haha, yeah I really like the way the LG 5K can extend the stand height to rise above the MBP display. That’s a really nice arrangement. In that configuration I like to use the MBP display for Terminal use and the LG display for my dev tools and web browser. Even better, with two 5K displays I can have the dev tools and web browser on separate screens which allows faster dev iteration

That's interesting. Do you have your two LG 5K's up top with your MBP below them? Just out of curiosity, do you just use those two dev screens or do you also use spaces to organize windows and programs into different containers on each screen?

I tried the multiple monitor approach several times and just found that I always ended up staring at one screen most of the time anyway. When I used a multiple display setup, my neck started to get stiff because I was always looking to my left where I positioned my main display. At some point I just decided to pack up my second monitor and use only one display because the presence of that second display wasn't really doing anything most of the time and was literally giving me headaches.

I've since developed a rather complicated regimen of allocating my programs and windows to different spaces. I switch back and forth between them quite fluidly most of the time, but when my MBP is struggling, the swap slows down and gets choppy and that slight hitch is enough to interrupt my flow when I'm doing something really intense. I'm hopeful the eGPU will address that.

I'm thinking of also trying the laptop under the 5K arrangement after I get the eGPU.

Well, first impressions are encouraging...If I do this for the display attached to the eGPU, the load appears on the eGPU and vice versa for the LG display attached directly to the MBP.

Thanks, that just made me a lot more comfortable to pick up one of these eGPUs this week.

 

[craig1410]

That's interesting. Do you have your two LG 5K's up top with your MBP below them? Just out of curiosity, do you just use those two dev screens or do you also use spaces to organize windows and programs into different containers on each screen?

I tried the multiple monitor approach several times and just found that I always ended up staring at one screen most of the time anyway. When I used a multiple display setup, my neck started to get stiff because I was always looking to my left where I positioned my main display. At some point I just decided to pack up my second monitor and use only one display because the presence of that second display wasn't really doing anything most of the time and was literally giving me headaches.

I've since developed a rather complicated regimen of allocating my programs and windows to different spaces. I switch back and forth between them quite fluidly most of the time, but when my MBP is struggling, the swap slows down and gets choppy and that slight hitch is enough to interrupt my flow when I'm doing something really intense. I'm hopeful the eGPU will address that.

I'm thinking of also trying the laptop under the 5K arrangement after I get the eGPU.



Thanks, that just made me a lot more comfortable to pick up one of these eGPUs this week.

Yeah my current setup is with my MBP open on the desk in front of me and far enough back so that the top of the MBP display is very close to the bottom edge of the primary 5K display. The MBP and primary 5K are both centred directly in front of me. The height adjustment on the LG 5K is enough to rise above the MBP display and I think this arrangement works well.

I then have the secondary 5K display off to my left with the bezels of the primary and secondary 5K displays almost touching and at the same height. The secondary 5K display is angled round so that it's perpendicular to my eyes when I turn my head to look at it.

I mainly use the primary 5K display for my dev tools (an IDE called RubyMine) and the MBP display is used for things like my Terminal or iTerm windows and Git-Tower SCM. My secondary 5K display is for things like development specifications and browser based project management stuff and reference material which I refer to during development. I also tend to push things like Skype and Slack away onto this secondary display.

Yes I also use spaces quite a bit because I like to focus on one thing at a time mostly and prefer to keep distracting apps like Skype/Slack in their own space which I refer to when I want to rather than have them grab my attention. I also like to separate the different workflows into separate spaces. For example, I might be coding, then testing, then checking code into SCM so these can run in separate spaces.

 

[smirking]

Well, I got my Blackmagic eGPU today and gave it a ride. I haven't made up my mind yet, but I think this one's going back. It barely does anything for my workflow. I did find that it sped up things like exporting large photo sets in Capture One Pro, but I don't do that very often and the exporting isn't usually time sensitive. Where it could have made a huge difference is by obliterating my render times to view RAW photos. My MBP was already doing ok in this area, but I was hoping an eGPU would make it near instantaneous so I could work at full speed in organizing my photo collection. If it sped anything up at all in this department, it was by an imperceptible amount.

I guess for the things I'm doing, a Radeon RX 480 actually does a capable job. The only thing the eGPU does is keep the fans on my MBP from spinning. That's worth something to me, but I don't know if it's worth enough for me to keep this. The one thing I dislike about having the eGPU is it makes disconnecting my MBP a chore. I get restless and like to roam from desk to elsewhere and back often and this gets in the way of allowing me to quickly grab and go.

I do have to say that it's gorgeous. I really like having it on my desk and it's quite nice as an external hub. I don't think this eGPU is overpriced at all. It's expensive and isn't the best value if you're looking at price to performance ratio, but it fills a different niche than a Razer X and is a reasonably priced premium product.

If we could get external CPU processors in a package like this, I'd get one in a heartbeat.

 

[craig1410]

Well, I got my Blackmagic eGPU today and gave it a ride. I haven't made up my mind yet, but I think this one's going back. It barely does anything for my workflow. I did find that it sped up things like exporting large photo sets in Capture One Pro, but I don't do that very often and the exporting isn't usually time sensitive. Where it could have made a huge difference is by obliterating my render times to view RAW photos. My MBP was already doing ok in this area, but I was hoping an eGPU would make it near instantaneous so I could work at full speed in organizing my photo collection. If it sped anything up at all in this department, it was by an imperceptible amount.

I guess for the things I'm doing, a Radeon RX 480 actually does a capable job. The only thing the eGPU does is keep the fans on my MBP from spinning. That's worth something to me, but I don't know if it's worth enough for me to keep this. The one thing I dislike about having the eGPU is it makes disconnecting my MBP a chore. I get restless and like to roam from desk to elsewhere and back often and this gets in the way of allowing me to quickly grab and go.

I do have to say that it's gorgeous. I really like having it on my desk and it's quite nice as an external hub. I don't think this eGPU is overpriced at all. It's expensive and isn't the best value if you're looking at price to performance ratio, but it fills a different niche than a Razer X and is a reasonably priced premium product.

If we could get external CPU processors in a package like this, I'd get one in a heartbeat.

Sorry to hear it's not working out for you as you had hoped. I wonder if it's just too soon for the apps you care about to have received updates from the software companies involved. Maybe some are waiting on refinements coming out in Mojave before they support the eGPU but of course there won't be any way to know for sure.

I'm actually tempted to install the Mojave Beta to see if that makes any noticeable difference to the way the eGPU operates, especially when undocking because I agree that is a little clunky at present. I find that when you tell the eGPU that you want to disconnect, it appears to shut down some apps which presumably were attached to that resource. For example I find it shuts down Skype and Slack and my RubyMine IDE for some random reason. Of course that might be due to the way those apps have been coded and I highly doubt those companies will be rushing to provide a fix given the esoteric nature of the issue.

It's definitely not a perfect solution but on the whole I'm still pretty happy and the reduction in MBP fan noise makes quite a difference to me I find, especially when only driving a single 5K display. That will almost certainly be reducing the contention for heat dissipation between CPU and dGPU which surely must be yielding more available CPU power. I should probably try to find a way to quantify that.

Overall I think I'm 90/10 in favour of keeping the eGPU but I still have some time to change my mind. I would probably suggest you keep using it for a few more days then try disconnecting it and see how your workflow feels without it. Sometimes you can better judge the effect of removing something than adding it. If you do decide to return it then there is probably no reason you can't try again later in the year once Mojave is out and app developers have had more of a chance to support it fully.

 

[smirking]

Ok, I just discovered something ridiculous. Not only is there no significant improvement in rendering of RAW image files in Capture One Pro when using the BlackMagic eGPU. I just realized that it's actually SLOWER. My guess is that an eGPU may introduce lag if you're doing something that has a high depdendancy on the CPU, which Capture One Pro appears to have. Zipping through a large photo catalog in Capture One Pro causes the fans on my MBP to roar even wth the BlackMagic connected. It doesn't roar as loud when my MBP is driving my 5K display alone, but it's still working quite hard considering the eGPU should be handling all of the graphics processing.

I did all of my comparisons in clamshell mode to make this more of a direct test of a Radeon RX 460 vs Radeon Pro 580. The 460 may actually be better at quick tasks that don't involve sustained load.

 

[craig1410]

Ok, I just discovered something ridiculous. Not only is there no significant improvement in rendering of RAW image files in Capture One Pro when using the BlackMagic eGPU. I just realized that it's actually SLOWER. My guess is that an eGPU may introduce lag if you're doing something that has a high depdendancy on the CPU, which Capture One Pro appears to have. Zipping through a large photo catalog in Capture One Pro causes the fans on my MBP to roar even wth the BlackMagic connected. It doesn't roar as loud when my MBP is driving my 5K display alone, but it's still working quite hard considering the eGPU should be handling all of the graphics processing.

I did all of my comparisons in clamshell mode to make this more of a direct test of a Radeon RX 460 vs Radeon Pro 580. The 460 may actually be better at quick tasks that don't involve sustained load.

My guess is that software developers (of which I am one) need to figure out how best to make use of eGPUs before that can reach their full potential. Your dilemma is whether to keep the eGPU and assist in this evolution or wait until others do it for you...

 

[smirking]

My guess is that software developers (of which I am one) need to figure out how best to make use of eGPUs before that can reach their full potential. Your dilemma is whether to keep the eGPU and assist in this evolution or wait until others do it for you...

Yeah, I concur. I would suspect that the state of eGPUs in general have issues like this. My use case appears to be a bit of an outlier so it never gets brought up. I didn't want more monitors, faster video render times, or more fps at max textures in a game. I wanted something that would speed up visually intensive interfaces to reduce the cognitive overhead of having to deal with a lot of information. The faster the screen shifts, the less energy I have to spend remembering what I need to know to finish the task at hand.

I'm rather fond of this eGPU even though it negatively affects performance where it matters the most for me. After once being the decibel beleaguered owner of the classic cheese grater Mac Pro that was constantly reminding me it was there, I'm so impressed at how quiet this thing is and how even quieter it makes my MBP.

This one is definitely going back, but I hope they keep releasing better ones and that software support gets more sophisticated. I'd be very interested in buying back into this in the future.