Is my iMac Broken? (Vega 48 Never In Use)

[adamjackson]

I edit RAW images in Lightroom Classic (latest version) and 4K videos (MPEG4/HEVC) in Final Cut Pro with a bit of Compressor thrown in sometimes and every time I open iStats, the Vega 48 is never being utilized. It was the same situation with the GPU in my 2015 iMac that this 2019 iMac replaced. I upgraded to Apple's best GPU and it's never utilized. Is my computer broken or are GPUs just not used for pro applications? What did I spend all of this money on? If I export a video, it's all CPU, same for importing, transcoding, color coding, editing RAW images, Handbrake, etc.

The only saving grace is that the VRAM is almost always maxed out. I'm on a 5K iMac and this is with my pro-apps running:

I just feel like I'm never using this GPU I paid for except for the VRAM. Is my machine broken?

 

[Nismo73]

Is it checked off to use graphics processing in preferences?

 

[jerwin]

If you run a metal or opencl benchmark (luxmark, say)-- does istat menu pick up on this?

 

[adamjackson]

Is it checked off to use graphics processing in preferences?

I've done Auto & Custom settings and it doesn't change the GPU usage.

If you run a metal or opencl benchmark (luxmark, say)-- does istat menu pick up on this?

Great point! Here's iStat during a GPU Benchmark in GeekBench

https://browser.geekbench.com/v4/compute/4450566

not a great score because I had a lot of things going on but it definitely registered
[doublepost=1566173812][/doublepost]I'm exporting a 35 minute 4K video 'master file" from FCP...ignore the initial GPU spike because that was Geek Bench

Here's CPIU + GPU history exporting from FCP & Lightroom simultaneously. All CPU:

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If my situation is not unique then here's a thread warning others if you use Lightroom and Final Cut Pro, don't bother on the Vega 48. it's a waste of money because Apple is selling us GPUs that don't utilize pro apps.

 

[jerwin]

Try "Enhance Details"

https://helpx.adobe.com/lightroom-classic/help/enhance-details.html

 

[adamjackson]

Try "Enhance Details"

https://helpx.adobe.com/lightroom-classic/help/enhance-details.html

Yep, that's definitely using the GPU! Thanks for the tip.

How can I force Final Cut Pro to Transcode & export faster by using the GPU? Does apple seriously ship Final Cut Pro and not support the Vega 48?

 

[Zandros]

Transcoding has historically not been an area that has seen much benefit from GPU performance. Many GPUs have dedicated decoding/encoding hardware (that won't really use the main portion of the GPU) which is really fast but will be lacking in quality compared to CPU based encoders.

I am led to believe that the main application for GPUs in video workflows is for effects work.

 

[priitv8]

I'm exporting a 35 minute 4K video 'master file" from FCP...ignore the initial GPU spike because that was Geek Bench
------
If my situation is not unique then here's a thread warning others if you use Lightroom and Final Cut Pro, don't bother on the Vega 48. it's a waste of money because Apple is selling us GPUs that don't utilize pro apps.

Don't know about Lr, but in FCPX Vega 48 is used when rendering the timeline and effects etc.
It does not take part in video encoding. I don't know, if it even contains the H.264 or H.265 encoder.
These tasks are handled by i9 HD Graphics CFL built-in GPU, or then not.

Both FCPX and Compressor make use of it. Also HandBrake.
It has hardware encoder with up to H.265 10-bit encode capability. Of which Apple VideoToolbox currently uses only 8-bit variety. All H.265 10-bit encodes still happen in software (CPU).
I posted my screenshot here: https://forums.macrumors.com/thread...oding-than-2017-i5-3-8.2189994/#post-27543971
Also, the Intel CFL meters are now gone from iStat menus. Have no idea if this is a bug or a feature: https://forums.macrumors.com/threads/istat-menus-on-2019-imacs.2187034/#post-27494786

 

[mikehalloran]

Does apple seriously ship Final Cut Pro and not support the Vega 48?

Of course it does — but only for those functions that benefit from acceleration.

In fact, if the 48 is not enough, you can add eGPU and have FCPx use it instead of the internal.
https://support.apple.com/en-gb/HT208544
For this, you must have eGPU and be running Mojave or later. This option is not available in High Sierra.

 

[ruslan120]

If you do get an eGPU, be sure to get at least a Vega 56 or wait for more powerful cards, something more powerful than the internal GPU. I say this because most apps that do* use eGPUs aren't fully optimized yet, and on occasion choose the external GPU even if it's less powerful.

Setup:
Vega 48 + RX 580

FCP: Speeds up - is smart enough to load balance when editing, splits tasks effectively, overall performance improves.
DaVinci: Slows down when rendering. Chooses the eGPU which in my case makes things slower.