Is internal GPU used at all?

[LopeDeAguirre]

Hi, I have an iMac 2020. It has a Radeon GPU, but also the CPU 10910 seems to have an internal GPU (UHD 630, I think). It takes a considerable part of the CPU die as one can see in pictures, and hence should cause a substantial part of the cost of the CPU. Now, I wonder if this internal GPU is used at all in the iMac or if it is wasting space. As the 10910 was created for Apple only, it might have been smarter to make a CPU without it in case it is not used. I mean, intel core CPUs without internal GPUs exist.

Does anyone know if it just idles all the time? What's the reason to have it?

 

[chscag]

Welcome to our forums.

You must be referring to the 2020 27" 5K iMac since there are no 2020 21.5" models. If you have 10910, then it's a core i9 CPU. The graphics (GPU) is discrete and not integrated with the CPU as some older 21.5" models were.

I believe you may be referring to the graphics memory which could be as high as 16 GB depending on which model you chose when you purchased the iMac.

 

[LopeDeAguirre]

Thanks for the welcome.

Indeed, I am referring to the 2020 27" 5K iMac. The graphics unit in this iMac is discrete, you are right. (That's the Radeon part I was referring to.) But there is also a GPU integrated in the CPU.

The die picture shows it. First the i7 with unit identifications

http://cdn.wccftech.com/wp-content/uploads/2015/08/Intel-Core-i7-6700K-Block-Diagram.png

and very similar the i9-10910

https://www.bestbuycpu.com/wp-content/uploads/2020/07/3RzUmxbTJdYUDBpsMeHxLS.jpg

(Integrated GPU on the right hand side this time)

It seems unused - what a waste. I just wonder if there is some functionality in the OS that makes use of it, even though all graphics are produced in the Radeon. 25% of the die permanently unused by the OS, really?

 

[pigoo3]

Now, I wonder if this internal GPU is used at all in the iMac or if it is wasting space...

It seems unused - what a waste.

Why do you think the integrated GPU is not used...and what proof do you have it's not used?

Computers with both an integrated GPU & discrete GPU have always been engineered so that the integrated GPU is used when doing less strenuous tasks...and the discrete GPU used when more powerful graphics/video tasks are done. It has always been this way.

For example...if you're checking email with the Apple Mail app...I can pretty much assure you ONLY the integrated GPU is being used.

Nick

 

[LopeDeAguirre]

If such a sophisticated load-balancing were possible, that would definitely be nice to have. I have my doubts, though, because the Intel Power Gadget never shows any variation in frequency: "GFX AVG = 0,00".

 

[pigoo3]

If such a sophisticated load-balancing were possible, that would definitely be nice to have. I have my doubts, though, because the Intel Power Gadget never shows any variation in frequency: "GFX AVG = 0,00".

Computers with both integrated & dedicated GPU's (especially laptop/notebook computers) have always been designed to only use the integrated GPU for less stressful tasks...and the dedicated GPU used for more stressful process's. Been this way for at least 10-12 years (maybe longer).

If you're using proper diagnostic methods to assess the use of the iMac's integrated GPU (when it's used & when it's not being used). Consider that maybe your individual computer has an issue. And if this is the case...take it to your nearest Apple store and have it looked at.

Nick

 

[LopeDeAguirre]

I think my computer is fine, thanks.

I did some testing and found the following. Hardware seems to be assigned to a task at Apple's discretion. With ffmpeg one can transcode
ffmpeg -i x.mkv -c:v h264_videotoolbox y.mkv
In the example, the videotoolbox seems to use Quicksync. At least the execution is quite fast and the "GFX AVG" goes up to 0.15, so I assume it is Quicksync, which I think is running on integrated GPU hardware.

[Fun fact: Trying instead
ffmpeg -i x.mkv -c:v hevc_videotoolbox y.mkv
shows "GFX AVG = 0,00", but it is still very fast. It seems to use not Quicksync on the iGPU but the T2 instead, because it features hardware hevc compression.]

Seems the hardware selection is transparent to the user and (of course) dependent on what is available, which makes sense.

Ok, at least the GPU hardware on the CPU can be made use of via libraries - maybe it happens also elsewhere.

 

[pigoo3]

If you really want to dig into this...you can use Activity Monitor to see the "GPU History" of the computer:

* Open Activity Monitor
* Click on the "Window" drop down menu.
* Select "GPU History".

Depending on how many GPU's you have available will determine how many readouts you'll get. Most folks that have more than one GPU will have an integrated & a dedicated GPU (2 readouts). Will look something like this:



I believe this Activity Monitor "GPU History" feature only works on newer versions of the macOS (possibly Mojave & newer).

For anyone reading...there's also a similar "CPU History" feature...which is available in older macOS version's.

Nick

 

[Slydude]

Thanks, Nick; I learned something new today. I've never noticed that GPU history feature in Activity Monitor before.

 

[pigoo3]

I think it's a new feature addition to Activity Monitor with newer macOS versions (possibly Mojave & higher). On one of my older computers running El Capitan there's no GPU history feature...but it is there on my 2017 MBP running Catalina.

There are some 3rd party apps that do this too. iStat Menu's ($9.99) I believe does this...as well as some others. But Activity Monitor is free (included with macOS).

Nick

 

[Slydude]

I've found some of the information in Activity Monitor quite useful --once you understand what they mean. For example, I've used the Memory Pressure graph to help me decide whether additional memory would help performance.

 

[LopeDeAguirre]

My macOS is BigSur (11.4). GPU history shows only the Radeon. Interesting.

 

[ferrarr]

Did you see this "Discrete graphics cards are not supported and GPU graphs will not appear unless Intel graphics is in use"?

I got that from here;

Intel® Power Gadget

Intel® Power Gadget is a software-based power estimation tool enabled for 2nd Generation Intel® Core™ processors or newer. It provides real-time processor package power information in watts using energy counters.

software.intel.com

 

[LopeDeAguirre]

I saw it. The tool links into the CPU and reads out some monitoring registers, I guess. External hardware is invisible. It shows "GFX AVG = 0,00" most of the time, so the internal GPU is not in use.

 

[chscag]

I saw it. The tool links into the CPU and reads out some monitoring registers, I guess. External hardware is invisible. It shows "GFX AVG = 0,00" most of the time, so the internal GPU is not in use.

I think there is confusion over this... The Intel CPU in your iMac and mine have a GPU integrated within it. In your case an i9 and mine as an i5 have this built in capability. However, since both your iMac and mine have discrete graphics (Radeon), the built in graphics is not used. Actually, it's probably turned off as there is no need for it.

The Activity monitor clearly shows that the internal GPU is not in use (0 % across the board).

I'm curious though, why are you even pursuing this? Are you concerned about the graphics performance of your iMac?

 

[pigoo3]

I think we need to back up...and re-read what Charlie mentioned in post #2. Typically Apple desktop computers (from the factory) typically only have one GPU (other than older Mac Pro's that can have multiple video card...and this is typically a dedicated GPU (no integrated GPU). Maybe in some older model entry level models there could possibly be an integrated GPU (to save money on an entry level model).

In this particular case with this model iMac...there almost definitely is no integrated GPU (at least one that's activated)...which is why no integrated GPU info can be seen/found.

Nick

p.s. About 5 seconds too slow (Charlie beat me to it)!

 

[LopeDeAguirre]

I think there is confusion over this... The Intel CPU in your iMac and mine have a GPU integrated within it. In your case an i9 and mine as an i5 have this built in capability. However, since both your iMac and mine have discrete graphics (Radeon), the built in graphics is not used. Actually, it's probably turned off as there is no need for it.

The Activity monitor clearly shows that the internal GPU is not in use (0 % across the board).

I agree.

I'm curious though, why are you even pursuing this? Are you concerned about the graphics performance of your iMac?

Not concerned about the graphics performance in itself, no, but GPGPUs are a thing. If the iGPU is part of the 10910, I'd rather use it than keep it deactivated. Because Apple is sort of a controlled, homogeneous platform, it would be easy for Apple to write libraries and make use of the iGPU in the background transparently. So whenever there is a sort or such thing, one would have highly parallel coprocessor doing it. I'd find this very cool, actually. Deactivating the potential would be sad, though.