300 MHz (3D core) / 400 MHz (VideoCore IV) difference?

Question

For the Raspberry Pi 3 it's mentioned here that the GPU has a 400 MHz (VideoCore IV subsystem) part and/or a 300 MHz (3D core) part.

BCM2837 runs most of the VideoCore IV subsystem at 400MHz and the 3D core at 300MHz (versus 250MHz for earlier devices).

Sadly, I don't understand what the difference is or how this is working.

• Does this mean the GPU has 700 MHz raw power?
• Or has two parts for two different jobs?
• Or works at 400 MHz for some jobs but only on 300 MHz for others?

Does anybody know and fully understand to explain?

Answer 1

The article is referencing two different circuits within the GPU that are meant to take two different tasks.

Does this mean the GPU has 700 MHz raw power?

No, the things don't just plug into each other to create Voltron. Which is unfortunate, because that would be cool.

Or has two parts for two different jobs?

This is what's happening. As the name suggests, the VideoCore handles the majority of the graphic applications the RPi needs to function. Most of the graphics handled by the RPi are in 2D, so it bears the brunt of the work.

The 3D core handles tasks that are related to 3D computing. If you're rendering 3D images, that's when you'll see the second component brought in. I imagine most people will only see this utilized if they're doing shape/facial recognition, or rendering models (either in Mathematica, or some Blender esq thing).