Understanding iGPU and OpenGL

Thanks in advance for any advice and help with this.

I’m on a Macbook Pro (2015/Catalina). When one particular app is up and sound libraries are loaded (I’m a musician), the fans on my computer ramp up to maximum and stay there for as long as I continue with the loaded project. When I asked tech support about why this is so, only with this particular software, I received a reply:

While I certainly understand thermal paste wearing out, I’m lost as to the references to the graphics card and what iGPU and OpenGL have to do with this, given that the fans ramp up and stay at max, only when using this one particular app. Am I to understand that this app is using OpenGL (whatever that really means), where all my other apps don’t?

Maybe someone here can shed some light on this?

Thanks in advance.


I’m assuming “secrete GPU” should be “discrete GPU”. That is, it’ll switch away from the “integrated GPU” to run on the “discrete GPU”.

To be honest, this sounds like a cop-out answer. From Apple’s website:

This is the reason that the laptop consumes more power, generates more heat, and runs the fans.

Fingering the API here is pretty lame. A Metal-based app doing the same things and generating the same load on the discrete GPU is going to generate a similar result.

Heh… yeah, let’s go with “discrete”…

As for it being a cop-out answer, that’s what I was wondering. But the point that is seemingly always lost on people is that the fans ramp up and stay there only with this particular app during this type of use. Yeah, of course, the fans may occasionally spin up through normal use, but never simply staying at max rpm’s for seemingly hours.

Thanks again for the answer and info. I’ll look into things.

One thing you might check is that VSync is enabled when running that app. That is, the application’s rendering rate is limited to the monitor’s display rate (e.g. 60Hz).

If VSync is “disabled” (on-the-other-hand), then both the CPU and the discrete GPU are going to burn lots of extra cycles and generate more heat, rendering frames at a rate much faster than you monitor can display. Typically only developers would use this mode, for app profiling purposes.

So I’d check your driver and app settings to ensure VSync is enabled.