Apple has one big reason to move to a homegrown GPU: It wants full control over the hardware and software in its devices.
The device maker is apparently developing its own GPU from scratch after dumping Imagination Technologies' PowerVR architecture, which is being used in the iPhone 7. The smartphone runs on the PowerVR A10 Fusion chip.
It's not certain when Apple's homegrown GPU will appear in devices, and the company didn't respond to request for comment.
Apple has made graphics improvement a priority in its iPhone and iPad models, so users should get better gaming experiences.
The homegrown GPU could also boost artificial intelligence capabilities on Apple's devices, and also bring on board features like image recognition.
Apple already uses its own CPU, and a homegrown GPU was the next logical step. The company has already developed its own storage controllers and wireless chips in a bid to cut reliance on external suppliers.
To build the best chip for devices, Apple needs to have control over all the critical pieces, said Jim McGregor, principal analyst at Tirias Research.
"Apple's looking at the iPhone and saying, 'How can we make it better?'" said McGregor.
Apple tunes its software to work hand-in-hand with its hardware. With the homegrown GPU, Apple will optimize the graphics to work closely with its Metal graphics API, which is similar to Microsoft's DirectX. Apple's iOS also supports OpenGL.
The GPU will add more versatility to iPhones and iPads, and likely push Apple into new markets, said David Kanter, president of Real World Technologies.
GPUs are being used to run digital assistants, image recognition, natural language processing, and other AI applications. Apple's GPU could be tuned for Siri, and also for image analysis and filtering in the Safari browser and other apps.
Apple will be able to harness the processing power of GPUs -- which are generally considered faster than CPUs -- to accelerate other applications. Apple supports the OpenCL parallel programming framework for Mac applications but has no iOS implementation yet.
The time had come for Apple to develop its own GPU as Imagination's PowerVR wasn't a good match for the iPhone 7. Though the A10 Fusion GPU was faster than the competition, it was too power hungry and couldn't sustain high levels of performance for long.
"We believe the iPhone 7, to avoid overheating, throttles back from its top GPU speed after a minute or less, preventing it from achieving a high score for all users," said analyst Linley Gwennap, of The Linley Group, in a research note in December.
Relying on Imagination Technologies for graphics was risky for Apple. Apple is a minority shareholder in Imagination, which has been rumored to be on the sales block. Moreover, Imagination wasn't the graphics chip leader it once was. Qualcomm, ARM, Nvidia, and other vendors offer mobile GPUs and have jumped ahead of Imagination in recent years.
Apple built up a team to design a GPU by poaching graphics experts out of Imagination, AMD, Nvidia, and Intel. The company is also looking to hire many graphics experts for Macs and mobile devices, with a focus on chip design.
The company has the patience, skilled employees, and resources to make its own GPU, Kanter said.
Apple's approach to bringing graphics technologies in-house has been gradual. It developed Metal, the compilers, and has been incorporating custom graphics cores that are now used in the iPhone 7.
Last year, Kanter's analysis of the GPU in the iPhone 7 led to a conclusion that the company was likely on its way to making a homegrown GPU. He found Apple making big changes in the GPU in the A10 chip's PowerVR architecture, such as a redesigned shader core. At the time, Kanter said Apple "could continue to customize more and more of their GPU – eventually designing out Imagination Technologies."
There are also rumors about Apple putting its ARM-based chips in Macs, which demand more graphics power. Designing a more powerful GPU that consumes more power can be complicated, and it's perhaps something Apple won't be chasing for now, Kanter said.
Apple's approach to developing a homegrown GPU is similar to that of Google. Google picked up data center hardware from regular suppliers, customized it, and eventually, made the hardware itself.
But challenges for Apple remain, particularly legal challenges from Imagination, which has questioned Apple's claim of developing an independent GPU technology.
Imagination did not accept Apple's claims, saying it would be "extremely challenging to design a brand new GPU architecture" from scratch without Apple infringing on Imagination's IP rights.
"Apple has not presented any evidence to substantiate its assertion that it will no longer require Imagination’s technology, without violating Imagination’s patents, intellectual property, and confidential information. This evidence has been requested by Imagination but Apple has declined to provide it," Imagination said in a statement.