GPU Usage - What's using it?

Hi Gang,

I’m wondering if there’s any way to tell exactly what’s using 83% of my GPU? I’ve been using iStat Menus for years, which provides a lot of useful information about what’s happening with my Mac (it’s kind of like Activity Monitor but on the Menu Bar). I recently added the GPU monitor, and wow, it’s always pegged, even when no applications are open. Unlike the other iStat menu displays, GPU doesn’t show what’s pegging it.

Does anyone have any ideas on how to determine what’s making the GPU go crazy?


I only have an integrated GPU, so I can’t check, but it seems that the solution from TidBITS might work:

Open Activity monitor
Go to the energy tab
Check on Requires High Perf GPU column

Those are processes which can be using your GPU


I’d seen that before, but the column in question doesn’t show or seem to exist for me. I added the GPU columns, and it shows Messages and Safari as using a bit of GPU. But as mentioned before, even with everything Quit, my GPU drops to about 50%.

Is the following perhaps an option?

Under what specifically in the “% GPU” column?

What do you have in the way of displays connected?

Activity Monitor doesn’t show the amount of GPU memory being used, only the processes that are using it.

According to iStat my CPU is currently at 11% (usage), while my GPU is at 86% memory at the moment.
Screen Shot 2020-05-05 at 2.47.50 PM

As you see here, there’s not much GPU processing going on, at the moment either.
Screen Shot 2020-05-05 at 2.48.14 PM

And over the last 30 days, you can that GPU memory has been consistently very high.

While GPU processing has been pretty low.

So, what’s using all of my GPU memory? I’m seeing some very unusual behavior in a photography application that I use, specifically around it not being able to draw the image when I Zoom in. Granted, I’m beta testing the app, but I want to ensure that the problem that I’m seeing, isn’t due to some weirdness that I’ve introduced.

John, it’s late 2014 27" iMac. I know that the video card in this is way under powered, and unfortunately Apple has removed support for eGPUs via Thunderbolt 2, so I’m out of luck in that regard.

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I don’t know if iStat is providing accurate info, but Activity Monitor definitely does. So… if you’re always at least using 50% GPU, for starters check Activity Monitor and see what processes are responsible.

Unfortunately, Activity Monitor doesn’t report which apps are using GPU memory, just how much GPU processing.

Can you post a screenshot? - Or are you only able to see that GPU graph and not a break-out by app?

EDIT: I see you can’t drill down to that kind of info in Activity Monitor; I was confusing its abilities with ATMonitor, which I used to use (until it stopped working a year or two ago).

If you’re really getting at least 50% GPU activity all the time the Activity Monitor graph should show it. If it doesn’t then I’d suggest not trusting iStat Menus results.

If your question targets the use of memory, then be aware of the following. From the perspective of the operating system, the GPU memory is only relevant for making information accessible for GPU computing.

In other words: information that processes on the GPU need quick access to is loaded here.

If there are no processes running, then memory management can choose to leave the information, as is. When a new process wants to use the GPU, then new information can be loaded (and old info can be removed).