iMac 2019 27 inch GPUs

Thanks in advance for answers.

My 2019 27 inch iMac has two GPUs.

CPU: Intel(R) Core(TM) i5-9600K CPU @ 3.70GHz

GPUs: Intel HD Graphics CFL + Radeon Pro 580X

The display is connected to the Radeon Pro 580x.

Is the GPU on the Intel CPU chip used for computation? Apparently I could use both in my own code developed using Apple Xcode.

Will the Canon DPP4 program use the Intel GPU for computation?

Canon DPP4 appears to me to use the Radeon GPU for display purposes according to Activity Monitor app.

Activity Monitor app does not seem to me to report on both GPUS.

Traditional Intel CPUID program: https://www.intel.com/content/www/us/en/download/674424/maccpuid.html

The CPU in my iMac: https://ark.intel.com/content/www/u...59600k-processor-9m-cache-up-to-4-60-ghz.html

JohnMoyer said:

My 2019 27 inch iMac has two GPUs.

• CPU: Intel(R) Core(TM) i5-9600K CPU @ 3.70GHz
• GPUs: Intel HD Graphics CFL + Radeon Pro 580X. The display is connected to the Radeon Pro 580x.

Is the GPU on the Intel CPU chip used for computation? Will the Canon DPP4 program use the Intel GPU for computation? Canon DPP4 appears to me to use the Radeon GPU for display purposes according to Activity Monitor app.

Click to expand...

Big difference in performance. Intel HD benchmarks about 1000 G3Dmark, 580x about 7000. If your 2019 iMac is similar to my 2014 Macbook running Big Sur 11, it does what Apple calls "Automatic graphics switching" (see Battery dialog) using Intel HD to conserve battery and Radeon 580x when needed for fast graphics. Nice! You can install 3rd party apps that switch.

No idea about Canon DPP4. You could try asking in a Canon forum. Yes, I would think DPP4 uses the real GPU for 7x or higher performance. In addition to being slow, Intel HD must share memory with the CPU, causing possible contention.

JohnMoyer said:

Apparently I could use both in my own code developed using Apple Xcode.

Click to expand...

Cool, I did not know that.

JohnMoyer said:

Activity Monitor app does not seem to me to report on both GPUs.

Click to expand...

Yes it can. Window > GPU History.

https://support.apple.com/guide/activity-monitor/view-gpu-activity-actm9329b315/mac

CAcreeks said:

JohnMoyer said:

My 2019 27 inch iMac has two GPUs.

• CPU: Intel(R) Core(TM) i5-9600K CPU @ 3.70GHz
• GPUs: Intel HD Graphics CFL + Radeon Pro 580X. The display is connected to the Radeon Pro 580x.

Is the GPU on the Intel CPU chip used for computation? Will the Canon DPP4 program use the Intel GPU for computation? Canon DPP4 appears to me to use the Radeon GPU for display purposes according to Activity Monitor app.

Click to expand...

Big difference in performance. Intel HD benchmarks about 1000 G3Dmark, 580x about 7000. If your 2019 iMac is similar to my 2014 Macbook running Big Sur 11, it does what Apple calls "Automatic graphics switching" (see Battery dialog) using Intel HD to conserve battery and Radeon 580x when needed for fast graphics. Nice! You can install 3rd party apps that switch.

No idea about Canon DPP4. You could try asking in a Canon forum. Yes, I would think DPP4 uses the real GPU for 7x or higher performance. In addition to being slow, Intel HD must share memory with the CPU, causing possible contention.

CAcreeks said:

Apparently I could use both in my own code developed using Apple Xcode.

Click to expand...

Cool, I did not know that.

CAcreeks said:

Activity Monitor app does not seem to me to report on both GPUs.

Click to expand...

Yes it can. Window > GPU History.

https://support.apple.com/guide/activity-monitor/view-gpu-activity-actm9329b315/mac

Click to expand...

Thanks!

The Intel GPU cannot be connected to a display on this iMac, but might be used for computation. I have seen example source code that uses the Intel GPU for inversion of a small matrix.

Activity monitor GPU history shows the Radeon Pro, but not the Intel GPU (maybe because it is not being used). A GPU that is separate from the CPU is usually much faster for video display, but a GPU that shares memory with the main CPU may be faster for computational tasks that fit within the 3rd level CPU cache because there is no need for communicating off chip between CPU and GPU and no need to transfer memory. These tradeoffs go back at least to the TI99 computer in 1983 which stored program and data in memory attached to the video chip and not in faster memory connected to the CPU.

CAcreeks said:

Big difference in performance. Intel HD benchmarks about 1000 G3Dmark, 580x about 7000. If your 2019 iMac is similar to my 2014 Macbook running Big Sur 11, it does what Apple calls "Automatic graphics switching" (see Battery dialog) using Intel HD to conserve battery and Radeon 580x when needed for fast graphics. Nice! You can install 3rd party apps that switch.

Click to expand...

An iMac doesn't need to conserve battery power.

Tom_N said:

CAcreeks said:

Big difference in performance. Intel HD benchmarks about 1000 G3Dmark, 580x about 7000. If your 2019 iMac is similar to my 2014 Macbook running Big Sur 11, it does what Apple calls "Automatic graphics switching" (see Battery dialog) using Intel HD to conserve battery and Radeon 580x when needed for fast graphics. Nice! You can install 3rd party apps that switch.

Click to expand...

An iMac doesn't need to conserve battery power.

Click to expand...

John did not indicate whether "Automatic graphics switching" was enabled. Perhaps an iMac has no Battery dialog? Anyway, I see both GPUs in GPU History. I'll have to try this on M2.



P.S. M2 not exciting; only one GPU.

CAcreeks said:

John did not indicate whether "Automatic graphics switching" was enabled. Perhaps an iMac has no Battery dialog? Anyway, I see both GPUs in GPU History. I'll have to try this on M2.

Click to expand...

A M2-based Mac will have only one GPU.