PlayStation 4K, what kind of performance can we expect?

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Reports from sources within Sony are claiming that the PlayStation 4.5, also dubbed the PlayStation 4K is real and already in the prototype stage.

4K gaming isn’t a realistic possibility

Let’s get one thing out of the way up front. Regardless of whether Sony calls this a PlayStation 4K, there’s no modern GPU that can pack into a console and offer a consistent 30 FPS at 4K within a $400 system price point. Teardowns of the original PlayStation calculated a $121 bill of materials (BOM) cost for its various processors. Even if we assume AMD’s next-generation Polaris architecture could deliver a 2.5x performance increase, the power envelopes and raw frame rates just don’t add up. Sony wasn’t willing to go deep into debt on the PS4’s hardware at launch (the console’s estimated bill of materials cost was $332 on a $400 launch price) and unless the company changes that philosophy, it’s going to be significantly constrained in what it can offer.

14nm should bring real improvements, but it’s not good enough in and of itself to drive the leap from 1080p to 4K. Our performance tests with Metro Last Light Redux illustrate why:

MetroLastLightRedux-Nano

Even top-end cards stagger when hit with 4K workloads. Granted, you could improve these figures by dialing back detail levels, but remember — the cheapest GPU on this list retails for over $300. Consoles are historically better than PCs at squeezing maximum performance out of lower-end hardware, but the GPU inside the PS4K still has to fit within that $100 – $120 price point.

WattsPer

The graph above shows the same Metro Last Light Redux test run, but this time calculates the number of watts used to produce each frame. A 2.5x increase in performance-per-watt would bring the Radeon Nano (AMD’s most efficient GPU to-date) down to 7.6W per frame — meaning you’d still need 230W of power for the GPU to drive a steady 30 FPS at 4K. And all of these assumptions are best-case ideals — real world targets are rarely so considerate.

The other problem with a 4K PS4 render target is that it would probably require significant CPU and memory upgrades. Remember, the entire point of a targeted console upgrade cycle is that you minimize hardware changes to make backwards and forwards compatibility as seamless as possible. Sony or Microsoft could get away with using a higher-clocked CPU, but shifting CPU architectures mid-stream would be a much more dramatic change. The PS4’s unified 8GB of RAM might not be enough to support AAA titles at 4K resolutions, which means you’d need either more GDDR5 or an APU that could support HBM/HBM2 — and neither of those solutions is currently cheap enough to fit within that aforementioned $80 – $120 price.

That said, there’s nothing stopping Sony from offering 4K output support through a hardware upscaler. This would add latency, but it could fulfill the 4K gaming bullet point without actually requiring dramatically improved horsepower.

If “true” 4K isn’t available, what can Sony offer?

Sony’s best bet with any hardware refresh is to focus on delivering significant gaming improvement at existing resolutions while simultaneously supporting 4K media playback. Upgrade the Blu-ray player to Ultra HD, add HDMI 2.0 support for 4K output, take advantage of the HDR support AMD is building in next-gen hardware, and you’ve got a potent upgrade option. 4K at 30 FPS might not be achievable, but 900-1080p at 60 FPS probably is. Again, take AMD’s claimed 2.5x performance per watt improvement and apply it to the watts-per-frame figures for 1080p — the final result would be 2.08W per frame, which would allow 60 FPS output for a total power consumption of around 125W. That’s well within console power consumption tolerances. At the very least, the PS4K should be able to hit a rock-solid 30 FPS at 1080p with no excuses or lag.

I’ve spent most of this article talking about the potential for a GPU upgrade because I think that’s where Sony is likely to spend most of its budget. In theory, a 14nm APU update could give the company a chance to switch to Zen or at least to squeeze more horsepower out of AMD’s Jaguar CPU. Obviously Zen is a black box at this point, but Jaguar is a known quantity.

NDPS4_8-640x476

The company could approach this from a number of directions, including a unified 8-core CPU block (eliminating the sizable performance hit currently incurred if one CPU block accesses the cache of the other), increasing clock speeds from the current 1.6GHz to something in the 2-2.4GHz range, and bringing the L2 cache clock up from the current 800MHz to either full CPU speed or at least increasing it to 1-1.2GHz to match the faster CPU cores. Other improvements could include an SSD storage option as at least one SKU, possibly at a higher price tag.

Would a PS4 with guaranteed 1080p output at 60 FPS and support for next-generation Blu-ray standards be enough to interest you? If not, what would it take?

[ExtremeTech]

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