Does the 2018 Mac Mini iGPU use up system memory when the VRAM is full?

[madlitch]

I just bought a 2018 Mac Mini, and I'm running an LG Ultrafine 5k

display and an LG Ultrafine 4k display. So far the iGPU has been pretty

bad at pushing that many pixels, but I'm not 100% sure if it's due to

the speed of the iGPU itself or its lack of VRAM. I'm not running very

graphics intensive applications. Currently, I bought the 8gb of RAM

model planning on upgrading to 32gb soon, but I'm wondering if it's

worth seeing if the upgraded system ram would increase the iGPU

performance. The system is using around 1gb of swap memory now (virtual

memory on ssd when physical memory is full).

 

[Stephen.R]

The iGPU in the 2018 has no vram, it just uses system ram (up to 1.5GB).

For 4K at least 16GB is recommended.

 

[madlitch]

The iGPU in the 2018 has no vram, it just uses system ram (up to 1.5GB).

For 4K at least 16GB is recommended.

So I would see an increase in performance if I upgrade to 32gb?

 

[Stephen.R]

So I would see an increase in performance if I upgrade to 32gb?

Yes, various people have experienced issues with hi-resolution displays and the base ram, which is resolved by upgrading memory

 

[madlitch]

Yes, various people have experienced issues with hi-resolution displays and the base ram, which is resolved by upgrading memory

Great, thank you. I'll update on its performance when I install the ram.

 

[xraydoc]

Great, thank you. I'll update on its performance when I install the ram.

Don’t expect dedicated-GPU level performance, but it should help a bit.

 

[oppastopa]

how are you able to run an LG 5k and 4k? do you just plug each monitor into a TB port?

 

[madlitch]

Don’t expect dedicated-GPU level performance, but it should help a bit.

Yeah I'm not trying to do anything super graphics intensive. The most intensive thing I would do is probably watch youtube. It's more so that the computer is actually usable with these high resolution displays.
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how are you able to run an LG 5k and 4k? do you just plug each monitor into a TB port?

Yeah, they both ran when plugged into separate tb3 ports. The four tb3 ports are split between two buses, just like the macbooks, and each bus has up to two displayport outputs. The 5k takes two displayport connections, while the 4k just takes one. I have them on opposite connectors.

 

[smirking]

Don’t expect dedicated-GPU level performance, but it should help a bit.

Yeah. Even on a loaded 2016 MBP, I had some occasional hiccups driving an LG 5K. It was fine most of the time, but there were a few scenarios in which I'd see things get a little choppy.

 

[madlitch]

Yeah. Even on a loaded 2016 MBP, I had some occasional hiccups driving an LG 5K. It was fine most of the time, but there were a few scenarios in which I'd see things get a little choppy.

My 2016 13" MBP with 16gb of ram was mostly fine at running the display. The mac mini with only 8gb however is struggling dearly.

 

[smirking]

My 2016 13" MBP with 16gb of ram was mostly fine at running the display. The mac mini with only 8gb however is struggling dearly.

I getcha. I didn't mean to imply that a full loaded 2016 MBP was struggling with it, but it just wasn't a total afterthought that it would run smoothly. I would notice dropped frames when I'd switch spaces sometimes. That could also have been influenced by other software too though. Where it definitely struggled was when trying to power the monitor and the MBP's screen at the same time. It worked, but wasn't too smooth.

 

[oppastopa]

when my mini 8gb arrived the lag with the Ultrafine 5k to me was minimal (I upgraded from a 2008 iMac which was on its last legs however) but I did notice it in launchpad.

upping to 32gigs and all of that went away.
pretty impressed the mini can push the 5k + 4k ultra fines. I was under the impression the mini could only support 1x5k and 1x4k but thru HDMI.

please do let us know how the system handles both ultra fines at 32gb!

 

[madlitch]

I have now upgraded the mac mini to 32gb of ram. The upgrade has helped a lot, now the system doesn't suffer when opening firefox or switching desktops. There is still a bit of choppiness when in the launchpad or switching desktops, but it completes it at around the same speed that a dedicated gpu would. As i'm only programming on it, and the most graphics intensive thing I would do on it is watch 4k youtube videos or edit photos, it is great for what I bought it to do.

 

[Susurs]

Is shared VRAM amount dependant on the RAM amount? Respectively, is 1.5GB possible with 8GB or only larger amount?

 

[Stephen.R]

Is shared VRAM amount dependant on the RAM amount? Respectively, is 1.5GB possible with 8GB or only larger amount?

The amount of memory for the iGPU is not fixed like in earlier models, but it seems extremely unlikely it'll assign nearly 20% of system memory to graphics.

 

[Susurs]

I wonder why it’s still @ 1.5Gb max for systems with 32GB or 64GB of RAM.

 

[Susurs]

P.S. Novabench 5/6 GPU test shows 1024MB VRAM on my MM 8GB. Anyone with 16GB or 32GB can see what this number is?

 

[Boyd01]

I see the same as your screenshot on my i7/64gb 2018 Mini. But perhaps this is because it only uses a 1280x720 window?

This is what System Information shows

 

[Susurs]

Thanks! Novabench is the same for all then.

I noted on activity monitor that memory usage with 8GB never go more than 6-6.5GB at max, so it means that even with 8GB 1.5 is reserved for GPU.