For those I’ve spoken to who watched Microsoft’s Xbox One press conference, one thing stuck out like a sore thumb (aside from lack of games) – the speed they rattled through the tech. Only general terms were used – 8GB of Ram, with no description to its type or speed, an X64 CPU – not word on the speed, a 500GB hard drive. It is a far different story to Sony’s press conference, who were only too happy to tell the world they’d the infamous 1.84 TFLOPS of computing power, and 176GB/s of bandwidth.
Shortly after, the press began to unravel just how close the Xbox One was to the rumored specs. As it turns out – pretty damn close. As a brief overview before we get started:
|Console Specs||Xbox One||Playstation 4||XBox 360 (for comparison)|
|CPU Type||AMD Jaguar X86-64||AMD Jaguar X86-64||IBM PowerPC|
|CPU Clock Speed||1.6GHZ (estimation)||1.6GHZ (estimation)||3.2GHZ|
|CPU Cores / Thread Count||8 cores / 1 thread each – 8 total||8 cores / 1 thread each – 8 total||3 cores / 2 threads each –
|GPU Cores||768 From 12 GCN||1152 From 18 GCN||Different Architecture|
|System Memory||8GB DDR3 2133MHZ||8GB GDDR5 5500MHZ||512MB 1400MHz GDDR3|
|Memory Bandwidth||68.3 GB/S for DDR3 + 102GB/S for the 32MB eSRAM||176GB/s Unified Memory||22.4 GB/s + 32GB/s from 10MB eDRAM|
|Peak Shader Power||1.23 TFLOPS||1.84 TFLOPS||0.24 TFLOPS|
As you can see from the brief overview, the CPU of the XBox One and the Playstation 4 are largely similar – the main divergence of the specs remain the Memory and GPU.
Xbox One and Playstation 4 CPU
I’ll be putting out an article and video that’ll go more into depth on exactly what the AMD Jaguar is and its architecture soon, but for now we’ll go into a basic overview of the chip. The CPU is designed to be a low power and low heat device, while providing the best performance possible. The Playstation 4 and Xbox One CPU is a part of a SoC (System on Chip) design, and for the most part the CPU design of the PS4 and XBox One are similar enough to where there is little difference between them. The chip is X86-64 bit, and features 8 cores. These 8 cores are split into 2 modules (so that would be 4 cores per module). Each module has 2MB of level 2 cache each (4MB total). The Jaguar is a follow up to AMD’s previous design, the Bobcat. In terms of raw performance vs a desktop, a high end PC (or even a medium range PC) won’t have anything to worry about in terms of raw performance numbers. The beauty of the design is the APU – which allows the GPU to handle some of the complex calculations which games are starting to require. Tasks which can be offloaded include but aren’t limited to: Physics, AI, Texture Streaming.
Currently we’re not 100 percent on what speed either Sony or Microsoft will be running the Jaguar at. The likely money is on 1.6GHz right now. The cores can be pushed all of the way up to 2GHZ in theory, but the higher you go, heat and power becoming an increasing concern. Both of these are obviously mortal enemies for console. The move from the PowerPC of both the Xbox 360 and Playstation 3 means a nuke to backwards compatibility. Ironically enough, the XBox One is actually compatible with the original Xbox, in theory at least. It would require software to allow it to do this however. The XBox 360 games would need to be completely ported. The XBox One containing an Xbox 360 SoC seems to be out of the window, which was a rumor flying about several weeks ago.
Xbox One VS Playstation 4 Memory design
Both systems agree that it’s important to have a decent amount of memory – 8GB, but when they start to talk about how it works, they both part ways. Sony’s approach is fairly easy to understand – 8GB of GDDR5 RAM, the RAM as we learned earlier is likely running at 5500MHZ. This gives you 176GB/s of memory bandwidth which is unified over the entire system. I have had the odd whisper from developers that the CPU only has access to about 20GB/s of bandwidth, but this rumor has little to back it up – so for now, take it with a pinch of salt. Regardless, there aren’t any caches or buffers in play here (aside from the L1 and L2 caches on the CPU of course). The memory is easy to access and use as developers need it. Although Sony did take a gamble here, let there be no mistake. The next generation needed at LEAST 4GB of RAM, and honestly – 8GB was what everyone really wanted. Sony had bet that GDDR5 manufacturing would have been smooth enough by the time the PS4’s release that memory modules large enough to be 8GB on the machine would be possible.
That isn’t to say that the GDDR5 RAM is perfect – it’s more expensive for one, and harder to source than DDR3. The only problem with it is that it requires more power. We’ll have to see if these things really matter. In the long term, the Playstation 4’s memory will become cheaper and cheaper to produce anyways.
The Xbox One however takes a different design. Due to Microsoft designing the system to use memory intensive applications (all of those media capabilities don’t come cheap) they needed 8GB of RAM. They decided to play it safe and go with 8GB of DDR3. They’re using 2133MHZ Memory, which is by no means slow. They achieve a peak of 68.3GB/s of memory bandwidth, but that is still far below what they need. Enter the 32MB of eSRAM. This memory sits on the CPU and GPU die, effectively acting as a fast buffer that can be used to shunt data around. It doesn’t sound that large when we’re talking about the ‘main’ memory of 8GBs, but the reality of the matter is that if used correctly it should have a decent hit rate. The trouble is that it leaves little room for growth, or for creativity in regards to the developers. In reality, the Xbox One has a benefit from the less graphical grunt – less memory bandwidth is required.
The XBox One also uses the ‘Move Engines’ to shunt data around the system without impacting the GPU or CPU performance. The benefit of this is simple enough – if the CPU and GPU are operating at their max output then the move engines are basically shuffling around data for free, and free up those operations that would otherwise eat up GPU or CPU resources further still.
Xbox One vs Playstation 4 Graphical Power and Performance
Unlike the memory system, where the Xbox One holds out hope that it will be able to keep up somewhat with Sony’s monster, the Xbox One can’t hold a prayer for the graphics side of things. Because MS went with DDR3, and therefore chewed up space on the SoC’s die for the Move Engines and the eSRAM, MS had to cut GCN cores down. Sony filled this space up with 18 GCN cores and 32ROPS, MS had to make do with 12 GCN cores and 16ROPS. There’s little that can be said here other than this has cost Microsoft dearly – both GPU’s are supposedly running at 800MHZ. This gives the Xbox One a peak performance of 1.24TFLOPS, compares to 1.84TFLOPS of the Playstation 4. Even if MS were to somehow run the cores at their max potential (1000MHZ), it still wouldn’t make up for the gulf between the 2 machines. Because of heat and thermals, I’d be surprised if they managed to ramp the speeds up this high – it’s likely they’ll manage 850MHZ tops.
1152 cores compared to the still respectable 768 of the Xbox one. It is worth noting that it’s still an improvement of about 5 times that of the previous generation (Xbox 360).
Stewart Gilray (boss of Just Add Water) recently said this in an interview:
“We might see slightly smoother framerates on PS4,” he said. “We’re working with Sony right now, and they’re trying to actively push 60 frames per second, 1080p. You might get situations where the graphics will be a little, but not much, lower quality on the Xbox One. Or, you might get some fixed at 30 frames per second situations in 1080p. It depends on the scale of the game. If your game is going to push the heck out of the PS4, you might have to do some little tweaks [for the Xbox One version]. But if you design your game to work on Xbox One at 60, it’s going to work on PS4 at 60.”
“The classic example is Devil May Cry on PS3,” Gilray explained. “There were some cases where they used a lot lower quality texturing compared to 360. That line will be blurred. It might be inverted on these two machines. It’s early days. The reason PS3 had slightly lower quality textures on some games with Unreal powered engines was because of the speed it moved around at. Now, with GDDR5 on PS4 it’s going to whiz around really fast. I wonder if that will be sacrificed a little bit quality wise with the DDR3 stuff on Xbox One.”
It’s a far different story from what developers and gamers were used to in the previous generation, when often the Xbox 360 version of the game was superior to what appeared on the Sony machine. On the PS3, often the versions would have lower internal resolution, worse frame rates, slower loading (thanks to the blu-ray drive) and more.
Time will have to tell just how much of a difference all of this makes to how games look and feel on the machine. I will put out another article and of course videos soon explaining more on the AMD Jaguar, and also hopefully with solid information on the clock speeds of both the systems GPU and CPUs when it becomes available!