Ever since the mid-generational PlayStation 4 upgrade was revealed, and then confirmed, the big story we've all been chasing is the complete lowdown of the hardware specification. We're still not entirely sure why Sony is looking to release a mid-gen upgrade to its massively successful console, but at least now we have a firmer lock on the technological boosts Sony is bringing to the table, courtesy of this Giant Bomb report.

First up, we should tackle the issue of how reliable the leak is and by extension, whether the proposed spec is real or not. Up until very recently, exposure to 'PlayStation 4K' throughout the development community was limited. We have been sitting on a number of details awaiting a second source before going to press, but events have overtaken us somewhat - Sony is now openly sharing this specification with developers and while Giant Bomb beat us to the punch, we have access to the same documentation. There is no doubt - this is real. This is the new, more powerful PlayStation 4.

The release window is unclear, but the schedule for hardware roll-out to developers is black and white: development kits prototype are on their way to studios now. A test kit (debug station, if you like) housed within a non-final chassis - which Sony is asking developers not to show - follows shortly. A second-gen test kit, again not based on the actual retail shell, goes out in June. Sony gives more intensive Neo briefings at its DevCon event in in May, while code submission for Neo-compatible titles begins in August.

But what of the actual spec? In our previous In Theory piece, we proposed three potential units - a tweaked 'PS4 Slim' based on the existing processor with added 4K media support, an enhanced version of the existing model, and finally, a no-holds-barred console that really pushed back boundaries. The reality? The new console - codenamed Neo - is essentially a hybrid of the second and third concepts and actually more powerful than I was expecting. Bearing in mind the technological and financial limitations inherent in designing a new console in partnership with AMD, it's pretty much the best we could have hoped for. The spec leak is confirmed:

This content is hosted on an external platform, which will only display it if you accept targeting cookies. Please enable cookies to view. Manage cookie settings Rich outlines everything we know so far about the Neo spec for the upcoming PlayStation hardware revision.

Base PS4 PS4K Neo Boost CPU Eight Jaguar cores clocked at 1.6GHz Eight Jaguar cores clocked at 2.1GHz 1.3x GPU 18 Radeon GCN compute units at 800MHz 36 'improved' GCN compute units at 911MHz 2.3x FLOPs Memory 8GB GDDR5 at 176GB/s 8GB GDDR5 at 218GB/s 24% more bandwidth, 512MB more useable memory

Let's take a look at the three core component upgrades:

CPU: The good news is that there will be a CPU upgrade over the lacklustre x86 cores found in PlayStation 4. The bad news is that the cores themselves have not been changed at all - they have simply been overclocked from 1.6GHz to 2.1GHz - a 31 per cent improvement. As with the current PlayStation 4, one core and a time-slice from another is reserved for the operating system.

Memory: We're still at 8GB of GDDR5, with a 24 per cent boost to bandwidth compared to the original PS4. The current machine uses 5.5gbps memory modules. Basic maths suggests that Sony has pushed this to the same 7.0gbps modules we see on high-end graphics cards like the GTX 980 and GTX 980 Ti. There are some concerns here. The boost to bandwidth isn't exactly huge, it will still be in contention with CPU utilisation (they both share the same interface), and the bandwidth doesn't scale particularly well with the mooted GPU boost, which - to be frank - is massive.

GPU: This is the most exciting aspect of the spec. Compute unit count doubles from 18 to 36, and clock-speed increases from 800MHz to 911MHz - a 14 per cent increase. That's an overall increase of 2.3x in FLOPs. The question is, what technology is being used here? AMD has created both of its current-gen console processors so far by taking older, off-the-shelf components and disabling a couple of compute units. In effect, Xbox One got the Radeon HD 7790, while PlayStation 4 got a more capable, semi-custom Radeon HD 7870. Here's where things get interesting - the 36 compute unit count cannot comfortably fit any of AMD's existing GPUs. It suggests that Sony and AMD have pushed the boat out, that they are using the upcoming Polaris technology.

Specifically, 36 compute units paired with a 256-bit memory bus sounds uncannily like the rumoured spec for one of two new Radeon graphics chips AMD has in development, codenamed Polaris 10. AMD itself hasn't revealed any official data on this processor yet, but canny enthusiasts have pieced together the spec by isolating Polaris 10's hardware ID from a Linus kernel submission, then comparing it to a Sisoft benchmark run. Curiously, this Polaris test run is carried out with an 800MHz clock-speed and 6gbps GDDR5 memory - a downgrade from the mooted PS4 spec. Some believe it may be the result of pre-production silicon, but it may also be a simulated run for a laptop variant of the processor where lower clocks are a prerequisite.

Assuming Neo benefits from AMD's new Polaris technology, we'll see a bunch of useful efficiency enhancements from the revised architecture as well as a raw boost to overall FLOPs.

We suspect the situation will become clear quite shortly, but for now, the balance of probabilities suggests that PlayStation 4K will feature AMD's next-gen graphics tech as opposed to older chip designs. Sony specifically says that an 'Improved AMD GCN' is used, giving us only two real alternatives to choose from - Polaris, which almost certainly has 36 compute units, or the older Tonga, which definitely has just 32. Sony's documentation mentions new GPU instructions exclusive to Neo, which would again support the idea of a more modern architecture. However, to play Devil's Advocate, we should stress that neither 14nm technology, nor Polaris itself are explicitly mentioned by Sony.

Our concern was that PS4's low-level APIs may not be compatible with the newer architecture, meaning problems running older games, but it seems that this is not an issue. And the good news here is that Polaris' efficiency improvements could add still further to the expected increase in performance. Certainly, we should expect to see cumulative improvements to memory compression, which should help us to get more out of the constricted 256-bit GDDR5 interface. To the best of our knowledge, there were no such technologies in place on the original PlayStation 4.

How two PlayStations will co-exist: Base and Neo modes Sony seemingly acknowledges the need to integrate the two models of PlayStation 4 available simultaneously on the market - internally dubbed as 'Base' and 'Neo'. There will be no games exclusive to the Neo model, every title will be available on both, and there's no suggestion of VR-exclusive Neo modes at this point. Developers are prohibited from creating Neo-exclusive gameplay features, and enhancements are expected to be graphical and performance-based in nature. Gamers on both systems will be tied into the same ecosystem, meaning that users of both models will be competing against one another in online games. The user interface and PSN systems will also be identical. The big question is just what is possible using the enhanced hardware. The need to support existing PlayStation 4 hardware puts a ceiling on the kind of experiences developers can offer - any kind of multi-platform development is defined by the lowest common denominator, and it's rare to find a developer that will dedicate significant resources to a small minority of users. This content is hosted on an external platform, which will only display it if you accept targeting cookies. Please enable cookies to view. Manage cookie settings Expect to see better performance for new - and patched - PlayStation 4 titles. Based on what we've seen of Final Fantasy 15, some games could really benefit. We just hope it doesn't open to the door to unoptimised code for older PS4 hardware. Well, according to Sony's own documents, there is a focus on delivering 4K gaming content, though upscaling to UHD resolution is likely. Owners of 1080p screens can expect benefits too, explicitly stated as: Higher frame-rates

More stable frame-rates

Improved graphics fidelity

Additional graphics features Sony describes 'forward compatibility' via patches, allowing developers to revisit their existing PS4 library and add Neo features to existing games. Sony has opened up more memory for Neo titles too. Quite why this extra RAM can't be given to games running in Base mode isn't revealed but Sony states that Neo titles will have access to 5.5GB of memory, with 512MB "only available" for Neo mode. Sony also reveals that the background media functions of the PS4 "might be" expanded - such as the addition of 1080p gameplay recording.

What isn't in PlayStation 4K/Neo In our original piece on PS4K, we suggested that Sony may be looking to add support for higher colour gamuts and high-dynamic range - part and parcel of the new UHD 4K spec and definitely supported in upcoming Radeon hardware from AMD. It is not mentioned at all in Sony's documentation, though the support should be there as the platform holder will be using AMD's display blocks. The omission says to us that it's simply not a priority at this time. There's also no indication at all that any of the functionality found in PlayStation VR's external processing box will make its way into the Neo hardware, nor is there any mention at all that Neo will benefit PSVR, though we would expect that the same base/Neo spec differentiation will apply to those titles just as they would to any PS4 game. On top of that, while the documentation says that the hard drive will remain the same (Sony has several in circulation, so we assume it means 2.5-inch laptop drives generally) there are no indications of any changes to the Blu-ray drive. This is surprising, as we would have assumed that Sony would take this opportunity to support the new UHD 4K movie standard, supporting standard 50GB discs along with 66GB and 100GB variants. For now it seems that developers are set to stick with 50GB of storage. There have been some murmurings of PSVR's external processing box being fully integrated into the new PlayStation. There's no indication that this is true, based on the documentation we have seen.