PS4 APU analysis reveals surprises

Sony PS4 teardown hardware

Sony’s Playstation 4 console has not only been torn down by iFixit and Sony, it’s also been analysed in detail by Chipworks, an engineering firm that specialises in chip design and reverse-engineering specialised technology.

Chipworks got their hands on a PS4 and subsequently destroyed it, but the gratuitous photographs of the insides of the APU are worth it.

The photographs reveal that AMD is not only using a full eight Jaguar cores in the APU, but they also included two extra sets of shader cores in the GPU to improve chip yields. This means that the APU actually includes twenty GCN (Graphics Core Next) shader modules – in other words, there’s a Radeon HD7870 tacked on in there.

In previous reports on the APU inside the PS4, it was discovered that only eighteen shader modules are active. To improve die yields, it appears AMD put in an extra two shader modules to make sure that even if the chips were slightly defective there would still be eighteen functional units available to the system.

Note that at no point will it ever be possible to use these extra two shaders on the APU. Despite the fact that such a thing is possible on the majority of hardware that AMD will produce for Sony, it won’t ever be used.

Another interesting feature is that the memory controllers are shared between all the components inside the APU. The processors can access any part of the PS4’s 8GB of system memory and the GPU can do the same, with both also being able to read the contents of each others’ memory sets.

Size-wise, AMD dedicates just 7% of the chip’s area to the processor cores, while the shader cores, including the disabled ones, take up 33% of the total chip area. It’s the most powerful APU AMD has manufactured to date.

Sony Playstation 4 APU made by AMD

Sony Playstation 4 APU made by AMD

Following the announcement that AMD was the manufacturer of the APU inside the PS4 back in February 2013, the company also announced that they would be selling an APU that would be the equivalent of the PS4’s APU.

AMD’s upcoming Kaveri APU comes closest to this design, with four Steamroller cores and eight shader cores, but it’s a long way off what the PS4 can do.

But that doesn’t mean AMD won’t ever make an APU that’s the equivalent to the PS4. Although the PS4’s APU is large and uses 150-190W of power on average, AMD can get that down to under 100W with some time and a die shrink to the 14 nanometer production process. That would put a successor to Kaveri somewhere in 2015.

At 14nm with four Excavator cores and a integrated HD7870 on the same die, that future APU could be almost three times as powerful as the upcoming A10-7850K. By that time we’ll have DDR4 memory chips as well.

That makes one wonder, though…what on earth will discrete graphics be like at that point?

Source: Chipworks

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PS4 APU analysis reveals surprises

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