Apple has built its own Mac graphics processors

Apple Silicon Macs will use an Apple-designed GPU – which makes complete sense and promises useful performance advantages.

Apple, WWDC, iOS, Mac, macOS, ARM, Apple Silicon

Like iPhones and iPads, Apple Silicon Macs will use an Apple-designed GPU – something that makes complete sense when you consider this is how current iOS devices work. But it could be a reason for pause by some high-end users during the transition period from Intel-based hardware.

Tile Based Deferred Rendering

You see, while Intel Macs contain GPU’s from Intel, Nvidia and AMD, Apple Silicon Macs will use what the company seems fond of calling “Apple family” GPUs. These use a rendering system called Tile Based Deferred Rendering (TBDR), which iOS devices already use.

It works differently from the Immediate Mode rendering system supported in Intel Macs: While the latter immediately render imaging data to device memory, the former makes more use of the GPU by sorting out each element first before submitting it to device memory. 

You can find out more here.

What advantages does it bring?

The effect is that TBDR rendering delivers lower latency, higher performance, lower power requirements and can achieve higher degrees of bandwidth. The A11 chip and Metal 2 really consolidated this technique.

Current developer-system Macs use an A12 chip, and Apple is now on course to deliver an even more powerful system in the iPhone 12’s anticipated A14 processor. 

It’s important to note that the GPU in a Mac with Apple silicon is a member of both GPU families, and supports both Mac family and Apple family feature sets. In other words, using Apple Silicon and Rosetta, you should still be able to use software designed for Intel-based Macs.

It’s a System on a Chip (SOC)

Another difference between (most) Intel and Apple Silicon Macs is the GPU. While Intel systems use a discrete GPU from other manufacturers, Apple Silicon Macs combine the processor, co-processors – including video encoders and decoders – the Neural Engine and machine learning accelerators onto one chip.

This means that graphics resources can be shared between CPU and GPU more efficiently with no overhead. It also means you can easily tweak iOS apps to run on Apple Silicon Macs.

Apple Silicon processors also carry high-efficiency audio coding, power management, storage controllers, the Secure Enclave, camera processor, and handle the cryptographic functions Macs currently use a T2 chip to support.

As a result, these systems can handle a great deal of work, all on processor, for fast performance and better memory bandwidth, power management and battery life.

One of the best ways to see the difference this makes is to run a high-performance Apple Arcade game such as Oceanhorn on both an iOS system and an Intel Mac. You won’t need to wait long until the Mac’s fan starts making a racket; in the future, that won't happen (so long as they run Apple Silicon and the apps are Metal native).

It’s not as if it’s news that Apple is going to make GPUs. 

Apple already makes its own GPU

Apple has been making its own GPU silicon for years. It replaced Imagination’s PowerVR tech , though subsequently reached a new licensing deal with the latter firm.

But making GPU tech that works well on an iPhone or iPad is one thing. Will it translate into performance advantages for Macs?

Early graphics performance tests concerning the new Apple Silicon suggest Apple’s eight-core A12Z running macOS 11 currently surpasses the integrated graphics of both the AMD Ryzen 5 4500U and the Intel Core i7-1065G7 chips. That’s promising,  given the imminent debut of Apple Silicon A14 chips.

The problem with the plan is when it comes to third-party GPUs from the likes of Nvidia, AMD or Intel; these (at least at the moment) will not be supported by Silicon Macs. This includes those external GPUs used by MacBook Pro and Mac Pro.

Apple’s argument may be that the need for such external GPU systems will be mitigated by the move to more powerful home-baked graphics technologies, which may be true.

The company has also committed to introducing new Intel-based Macs that do support these external systems for some time during the current transition.

What's up next?

We already know Apple Silicon Macs are going to be fast. We now know the performance enhancements will extend to the graphics systems – and can speculate that future Macs will be high-performance systems that consume less power than before.

How will Apple exploit this? Will it ditch fans in order to make thinner Macs? Will it exploit the opportunity to explore a new design language for its PCs? At what point will an iPhone become all the Mac you ever need, given your choice of user interface and access to a larger screen?

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Copyright © 2020 IDG Communications, Inc.

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