



The specs for Sony’s successor to the Playstation brand, the PS4 will feature parts from AMD. Advanced Micro Devices are supplying both the GPU (graphics processing unit) and the CPU for the new system. The CPU, AMD’s Jaguar, is 2×4 core clusters running at 1.6GHZ and providing enough multhreading power to deal with pretty much any games out there. The GPU however, uses the ‘new’ (AMD are working on the Radeon 8000 series for the PC) 7970M, or at least a version of it.

What are the GCN cores that make up the 7970?

The 7970 (in the PS4, the Mobile and the Desktop version all use a new AMD architecture called GCN. These GCN’s are (Graphics Core Next) serve as the architectural basis for AMD’s future GPUs. This is true of discrete products (such as say the version which would plug into your desktop PC’s PCIE slot) and integrated solutions. These will be placed alongside the CPU – and become so called APU’s. These cores are highly scalable and fantastic at compute calculations along with the traditional role of being able to push pixels onto screen – in other words, play games. This is the logical direction for AMD to go, as the market for graphic and compute functionality is becoming increasingly demanding.

7970M vs the desktop Radeon 7970

The M (meaning Mobile) is a lower power variant that you can buy for your desktop. There are a few key differences between the Desktop to Mobile (which would typically be used on say a laptop) and the version present in the PS4l. The Desktop version is more powerful – due to a number of factors. Size (both of the card and the GPU die itself) aren’t such a concern. This means that heat and power draw are far less of a concern. in turn, this means AMD have managed to squeeze more onto the GPU. The desktop version comes equipped with 3GB of GDDR5 RAM, the core is running at 925MHZ, with 32 Compute Units (GCN cores), 2048 stream processors, and 32 ROPS and 128 texture units.

The mobile Radeon 7970 is cutdown from this. We see the 7970M running with only a clock speed of 850MHZ, and with 20GCN cores. 2GB of GDDR5 RAM and 1280 stream processors. 80 texture units survive the cull from the desktop version of the AMD Radeon 7970 3GB (amazon link) 2.17GLFOPs of computing power for the 7970M, compared to 3.79 for the full desktop Radeon 7970.

Below is a table showing off a few of the key features of the 2 GPU’s on a side by side basis.

Radeon 7970M Radeon 7970 (desktop) 850MHZ Core Clock 925MHZ Core Clock 2GB RAM GDDR5 3GB RAM GDDR5 20 GCN Compute Cores 32 GCN Compute Cores 80 Texture Units 128 Texture Units 32 Color Rops 32 Color Rops 2.176GFLOPS (single Precision) 3.79GFLOPS (single precision) NO L2 Cache 512KB L2 Cache 1280 Stream Processors 2048 Stream Processors

PS4 GPU Compared to the 7970M

The playstation 4 on the other hand, needed to cut things back further. Remember – the PS4 has a performance figure of 1.76GFLOPS (once again, single precision). that’s a lot of difference from the original desktop version – although not a million miles away from the Radeon 7970M Laptops (amazon link). The speed of the GPU is reduced even further, from the 850MHZ to 800MHZ. Fortunately, we still keep the 32 ROPS of the mobile and desktop versions of the AMD 7970, BUT we lose another 2GCN cores (bringing the total down to 18 for the PS4 – the Xbox 720 is rumoured to have fewer still, only 12). GONE is the dedciated RAM for the GPU. The PS4 uses 8GB of GDDR5 RAM, which is unified (tied in to the CPU and GPU). This RAM runs at 176GB/s while the 7970M has 2GB of GDDR5 that’s giving 153GB/S of bandwidth. Remember though – the GPU and CPU of the Playstation 4 share this RAM, meaning despite the max bandwidth being higher, the amount that the GPU will have ‘available’ will likely be considerably lower than this.

Before anyone goes on a “PS$ sucks” rant – it doesn’t. You’ve got to remember the reasons Sony have gone with this. The first, is that the PS4 is a CLOSED spec. If you buy a PS4, and your friend 2 years later buys one, other than possibly a bigger HDD or a more refined manufacturing process, the system will be the same. You’ll not find your CPU slower than his. This also means that developers can write games to take full advantage of the hardware – not need to worry about different revisions of drivers, hardware and even OS versions.

The next is heat and power – it’s even more of a concern in a console than it is a laptop. Remember that the RROD fiasco with the Xbox 360 was caused mostly because of heat (and Microsoft cutting costs during the production). Cutting the size and power draw of the chip mean that you’re less likely to see your new PS4 crash and burn. It also means it’s easier to design the cooling system, meaning it needs less of it – shrinking the size of the system. It also will increase yields – in other words, more chips will actually work at the speeds needed (meeting the required bin) rather than not quite cutting it. This will decrease costs of the console (due to more of the wafer being useable) and more systems available at launch. All of which are extremely important factors.

Quite simply put, you can’t expect a Playstation 4 to have a 250W GPU in it – that the Radeon 7970 would be (not the mobile version) otherwise. This GPU will have plenty of power to play the games at 1080P – although this will change of course several years after launch. Crysis 3 for example runs at 1024×720 on console, upscaled to 1280×720 (OR 1920×1080) on the PS3. The Xbox 360 version runs natively at 1152×720 (upscaled to either 720 or 1080P). If you’re curious as how this works, check out this article on wiki for anamorphic widescreen. You can also use Doom 3 engine games (so that’d be Doom 3, Quake 4 and so on) to test it out, by changing FOV along with resolution using console. I’ll let you google about that though 🙂

Overall the PS4 and Xbox 720 are hugely ahead of the current generation of consoles. The xbox 360 runs at 240FLOPS of GPU power, compared to the Playstation 4’s 1760. So that’s around 7.33 times the difference!