Straight-up eGPU question to end them all

[arctair]

Ok, once and for all, this is the answer I need:

Let's say I have an iMac and Mini (assuming most recent releases) with the exact same internal specs (minus whatever onboard video exists): Same chipset, same chip speed, same memory, same 1 GB internal SSD, same things I'm forgetting, etc. I know this isn't exactly possible, but you can get close.

On the iMac, I'm driving a single built-in 5K monitor with a built-in Radeon Pro 5700 XT with 16GB of GDDR6 memory. I'm editing (RAW photos and videos); I'm rendering them.

On the Mini, I'm driving a single (almost identical, from what I understand) LG UltraFine 5K monitor with a Radeon Pro 5700 XT with 16GB of GDDR6 memory inside a Razor Core X over TB3. Let's assume the most current version of Catalina or Big Sur fully and robustly supports eGPUs. I'm editing (RAW photos and videos); I'm rendering them.

Theoretically and/or practically, am I going to have a different experience, and if so, why?

Going one step further, when AMD comes out with its next big thing, am I not going be able able to swap out the 5700 XT, add a bigger PSU if necessary, and be better off than the iMac?

I know this has been touched upon and, in related ways, discussed at length on other (older) threads, but I need -- at least to start -- a binary answer, circa late October 2020. Hence the poll.

Thanks y'all.

 

[IngerMan]

I had a few iMac’s. Most recent 2015 27”. I now have a MM 2018 i7 with a Vega 56 eGPU 38” Dell 4K.

What I loved about the iMac was simplicity, it just worked. What I hated was it’s only 27” and the ports in the back.

What I love about the MM is the Screen, the Screen. What I hate is it doesn’t always work smoothly with eGPU like the iMac.

I would go iMac if they had a 32” -34“ option, otherwise I am staying MM.

 

[arctair]

I had a few iMac’s. Most recent 2015 27”. I now have a MM 2018 i7 with a Vega 56 eGPU 38” Dell 4K.

What I loved about the iMac was simplicity, it just worked. What I hated was it’s only 27” and the ports in the back.

What I love about the MM is the Screen, the Screen. What I hate is it doesn’t always work smoothly with eGPU like the iMac.

I would go iMac if they had a 32” -34“ option, otherwise I am staying MM.

So when you say the screen, I assume you're talking about not being limited to 27". Do you game? I'm currently driving a single curved 32" 4K monitor with my, as I call it "hospice" Late-2012 mini, and I... ha... "strongly dislike it." I'm gonna need a neck brace. Maybe if you game there's a tendency to constantly looking left and right that the curve actually benefits, but I don't know what I was thinking. I've I've come to realize that my 25" 1440p was my favorite monitor ever. Would love to see a 5K at that size, but I know there are scaling maths and also people just like big.

For my primary, right in front of my face monitor, I like to be able to move just my eyes, not my head.

Enjoyable tangent, but let's get to the point: In what ways "doesn't always work smoothly"? The Vega 56 isn't state-of-the-art, but it's no slouch. What eGPU are you using?

38" at 4-5 ft makes me cry lol. Also assuming your vote would be "vastly different".

 

[theSeb]

Theoretically this question is easy to answer. An eGPU is connected via TB3, which has the bandwidth equivalent to PCIe X4. A graphics card connected directly on the motherboard will be using PCIEx16. So that is 4 times the bandwidth.

Adjusting for GPU Memory Bandwidth Tradeoffs | Apple Developer Documentation

Choose a suitable GPU and memory storage mode for tasks based on that GPU’s memory bandwidth on a Mac.

developer.apple.com

Therefore you will have a worse experience using the eGPU solution

Practically though the question is much harder to answer. Just how will this bandwidth limit impact you depends on what you are doing. In games you will certainly be losing some frames. I cannot tell you exactly how many because direct comparisons are hard to find for that particular graphics card.

Take a look at this video for a comparison of the RX580. In some games it's almost nothing, in others it's around 5 frames difference and in some games it's 10

But the RX580 is around 45% slower than the 5700 XT, so, in theory, it will be more impacted by the bandwidth restrictions.

 

[richinaus]

Theoretically this question is easy to answer. An eGPU is connected via TB3, which has the bandwidth equivalent to PCIe X4. A graphics card connected directly on the motherboard will be using PCIEx16. So that is 4 times the bandwidth.

Adjusting for GPU Memory Bandwidth Tradeoffs | Apple Developer Documentation

Choose a suitable GPU and memory storage mode for tasks based on that GPU’s memory bandwidth on a Mac.

developer.apple.com

View attachment 975306
Therefore you will have a worse experience using the eGPU solution

Practically though the question is much harder to answer. Just how will this bandwidth limit impact you depends on what you are doing. In games you will certainly be losing some frames. I cannot tell you exactly how many because direct comparisons are hard to find for that particular graphics card.

Take a look at this video for a comparison of the RX580. In some games it's almost nothing, in others it's around 5 frames difference and in some games it's 10

But the RX580 is around 45% slower than the 5700 XT, so, in theory, it will be more impacted by the bandwidth restrictions.

It is definitely noticeably slower on an egpu than internal, due to the bandwidth.
Also eGPU is a pain in the arse.
But I also prefer not to have an AIO...... its really just weighing it all up I guess.
Also benefit is you can upgrade an egpu.

 

[IngerMan]

So when you say the screen, I assume you're talking about not being limited to 27". Do you game? I'm currently driving a single curved 32" 4K monitor with my, as I call it "hospice" Late-2012 mini, and I... ha... "strongly dislike it." I'm gonna need a neck brace. Maybe if you game there's a tendency to constantly looking left and right that the curve actually benefits, but I don't know what I was thinking. I've I've come to realize that my 25" 1440p was my favorite monitor ever. Would love to see a 5K at that size, but I know there are scaling maths and also people just like big.

For my primary, right in front of my face monitor, I like to be able to move just my eyes, not my head.

Enjoyable tangent, but let's get to the point: In what ways "doesn't always work smoothly"? The Vega 56 isn't state-of-the-art, but it's no slouch. What eGPU are you using?

38" at 4-5 ft makes me cry lol. Also assuming your vote would be "vastly different".

Yes I really enjoy the larger screen. Especially when having full size documents side by side by side, with a little room left over. I would be disappointed going back to 27", I had that for almost 3 years. Now I could go 32 - 34, and if they did that with a 5k iMac, I would have interest down the road.

Im using a Asus RX Vega56 Asus XG Station Pro. I game sporadic, last was the Shadow of the Tomb raider and the eGPU made a pleasurable experience. I use to always leave it on, but lately I just keep it off. Gaming is the only reason for me to have it at this point. I have FV on so the restart when using the eGPU is very inconsistent, sometimes it works but most times it force shutdown because of blank screen, turn off the eGPU then restart back up, turn eGPU back on.

 

[arctair]

Theoretically this question is easy to answer. An eGPU is connected via TB3, which has the bandwidth equivalent to PCIe X4. A graphics card connected directly on the motherboard will be using PCIEx16. So that is 4 times the bandwidth.

Adjusting for GPU Memory Bandwidth Tradeoffs | Apple Developer Documentation

Choose a suitable GPU and memory storage mode for tasks based on that GPU’s memory bandwidth on a Mac.

developer.apple.com

View attachment 975306
Therefore you will have a worse experience using the eGPU solution

Practically though the question is much harder to answer. Just how will this bandwidth limit impact you depends on what you are doing. In games you will certainly be losing some frames. I cannot tell you exactly how many because direct comparisons are hard to find for that particular graphics card.

Take a look at this video for a comparison of the RX580. In some games it's almost nothing, in others it's around 5 frames difference and in some games it's 10

But the RX580 is around 45% slower than the 5700 XT, so, in theory, it will be more impacted by the bandwidth restrictions.

The PCIe connection difference was an obvious overlook. I read so much about TB3 recently I think i convinced myself it was just as fast as anything plugged right into a motherboard bus.

It also means that theoretical card upgrade in the eGPU would probably result in nothing. Unless...

In a game, we're talking about non-stop rendering of frames. The card is getting hit as fast as it can. Editing and rendering small videos — even if they're say 8K — the card is getting that in something less than real time, so the question is does your bandwidth restriction problem come into play more with gaming, or across the board (pun intended).

 

[theSeb]

I would say probably not. But take a look around all the various issues people are having with their eGPUs on these forums before making any decisions.

 

[arctair]

Thanks for the straight answer. I have looked around; it seems many have been monitor recognition issues — many seemed to have been resolved with late versions of Catalina (or there is a sense of hope/people have found in the beta) that they are resolved. Also usually involve disk monitors. But unfortunately it looks like I'm not gonna get what I want — I'm either gonna regret eGPU issues with the Mini, or the fragile, non-upgradable (and big $ up front, with the fear I can get my current work done with a maxed Mini sans-eGPU) fragile behemoth that is the 27" iMac.

 

[CC88]

I'm in the club of the people who have eGPU issue with MM2018.

I have constant kernel panic related to eGPU after wake up (the log talk about some AMD driver etc). I'm using a Razer Core X and Sapphire Nitro+ 580.

After several days of use I can't get it to work as stable as I need. Luckyly my Razer was bought from Amazon and today I made the decision to give it back.

 

[weaztek]

I retouch 16-bit, 30 megapixel RAW files (160MB files) everyday and I have a Mini and an RX 570 card with only 4 GB VRAM. Photoshop operations like the healing brush, clone stamp tool, liquify, etc. are pretty much in real-time. So Photoshop performance is not really going to get faster than doing things in real-time.

The new AMD card is out this week and it's an absolute monster.

But to my point. If you are concerned about photo editing you can't go wrong with either solution-both will be extremely capable machines. If you want a gaming machine I can't comment because I don't know the answer to that.

 

[arctair]

I'm in the club of the people who have eGPU issue with MM2018.

I have constant kernel panic related to eGPU after wake up (the log talk about some AMD driver etc). I'm using a Razer Core X and Sapphire Nitro+ 580.

After several days of use I can't get it to work as stable as I need. Luckyly my Razer was bought from Amazon and today I made the decision to give it back.

Well, it's definitely on the compatibility list. Ws anyone else able to give you any indication of what might be going wrong before you returned it? Will you simply be working with the onboard graphics now, or upgrading to something besides the 2018 Mini?

 

[arctair]

I retouch 16-bit, 30 megapixel RAW files (160MB files) everyday and I have a Mini and an RX 570 card with only 4 GB VRAM. Photoshop operations like the healing brush, clone stamp tool, liquify, etc. are pretty much in real-time. So Photoshop performance is not really going to get faster than doing things in real-time.

The new AMD card is out this week and it's an absolute monster.

But to my point. If you are concerned about photo editing you can't go wrong with either solution-both will be extremely capable machines. If you want a gaming machine I can't comment because I don't know the answer to that.

I wonder if you're having less issues because you're using an all-in-one GPU that comes with the card built in. Which new card that came out this week are you referring to? I'm starting to think that these aren't eGPU issues, but eGPU box/card combo issues.

 

[CC88]

Well, it's definitely on the compatibility list. Ws anyone else able to give you any indication of what might be going wrong before you returned it? Will you simply be working with the onboard graphics now, or upgrading to something besides the 2018 Mini?

I'm thinking of buying another box and another card. But, box and card in the list below:

Use an external graphics processor with your Mac – Apple Support (AU)

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

support.apple.com

Box could be another Core X (in any case I have returned mine) and a card of Pulse family instead of a Nitro+.

Sure I'm not an AIO man

 

[arctair]

I'm thinking of buying another box and another card. But, box and card in the list below:

Use an external graphics processor with your Mac – Apple Support (AU)

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

support.apple.com

Box could be another Core X (in any case I have returned this one) and a card of Pulse family instead of a Nitro+.

Sure I'm not an AIO man

Ah I didn't notice that Nitros weren't one the list; Pulse def is

 

[AlumaMac]

I'm in the club of the people who have eGPU issue with MM2018.

I have constant kernel panic related to eGPU after wake up (the log talk about some AMD driver etc). I'm using a Razer Core X and Sapphire Nitro+ 580.

After several days of use I can't get it to work as stable as I need. Luckyly my Razer was bought from Amazon and today I made the decision to give it back.

I have a 2018 MM, Razor Core X and Sapphire Nitro 5700XT and (knock on wood) have had no issues as of yet. Are you running Mojave or Catalina?

 

[CC88]

I have a 2018 MM, Razor Core X and Sapphire Nitro 5700XT and (knock on wood) have had no issues as of yet. Are you running Mojave or Catalina?

I'm running Catalina 10.15.7. Tried Mojave but it was even worse... With Mojave when I tried to eject my eGPU the system shutdown immediately. Also the sleep function no more worked, immediately wake up but no more signal on the monitor. A disaster.

 

[weaztek]

I wonder if you're having less issues because you're using an all-in-one GPU that comes with the card built in.

That's a good question. Thought it works great on my machine, that might not be universal. I'm thinking there could be software/firmware conflicts or something.

The good news about iMacs is they are guaranteed to work really well with the built-in graphics cards. That's the beauty of them.

Which new card that came out this week are you referring to? I'm starting to think that these aren't eGPU issues, but eGPU box/card combo issues.

AMD Radeon RX 6000 is an absolute beast. It will be a while before it's supported for Mac, but high-performance graphics cards are the new black.

 

[CC88]

Well maybe I'm in this case:

Apple's macOS Catalina causing problems with select eGPU setups | AppleInsider

Despite overall feature and performance improvements for external GPUs, the new macOS Catalina is now failing to work correctly with certain combinations of Mac and GPU card.

appleinsider.com

and 5700XT is not affected...

 

[weaztek]

If that article is a year old as it says, it shouldn't still be relevant on Catalina.

 

[MevetS]

I have a 2018 Mini and use a Razor Core X with a Sapphire Pulse RX 580, and while I have had issues in the past I have a stable set up now. I run two displays via the Razor and one via the Mini's HDMI port. I'm using the latest version of Catalina.

The display connected to the Mini gives me the start up screens and the system boots up fine. Previously I was using a HDMI plug in the Mini, with two displays on the eGPU. No start up screens but it would boot up fine (the full steps to make this work can be found elsewhere on this forum). Prior to using the HDMI plug I could not boot with the eGPU without plugging and unplugging things, highly non-optimal.

Others on the forum have reported that with the latest update to Catalina they no longer need to use the Mini's HDMI port and can boot without issue using only the eGPU. I've not yet tried connecting all three displays to the eGPU.

Good luck whatever you decide.

 

[CC88]

Maybe there was something faulty on my setup. Without the eGPU at the moment no kp after wake up. Finger crossed.
Also the RX580 pulse is in the apple compatibility list (the nitro+ is not mentioned at all). Maybe they differ in firmware or other components. I don't know.

I'm looking for a stable eGPU configuration now I will go only for brand and model suggested by Apple.

 

[theSeb]

Besides issues ejecting , are you having problems when just using the eGPU?

 

[arctair]

That's a good question. Thought it works great on my machine, that might not be universal. I'm thinking there could be software/firmware conflicts or something.

The good news about iMacs is they are guaranteed to work really well with the built-in graphics cards. That's the beauty of them.

The bad news is I don't like my computers to be composed mostly of expensive glass. So, I am going to try a Razor Core X (ordered) with some variant of a Sapphire RX5700 (not ordered; currently shopping) with a 3.2GHz 6‑core 8th‑generation Intel Core i7 (in cart, with the Late-2012 as a trade-in discount of $160; not ordered, in cart). We'll see how it turns out.

The good news about iMacs is they are guaranteed to work really well with the built-in graphics cards. That's the beauty of them.

Which is why I wonder if Apple will continue to support newer AMD cards unless they actually end up inside an iMac, Pro, etc.

AMD Radeon RX 6000 is an absolute beast. It will be a while before it's supported for Mac, but high-performance graphics cards are the new black.

There you go... and very true, which is why I hope not being for sure stuck with a 5700 inside an iMac is the smart move. (Knowing that in reality, it could be all I really need for next ten years. But like I said, I like seperate components, and I don't like my computers made of glass lol.

 

[IngerMan]

That sounds like a very good robust system. The only problem you might find, and a small problem is file vault on and power up. Its not huge pain. Its an easy work around. But it is a work around. Congrats.