CPU & GPU Hardware Analyzed

Although Microsoft did its best to minimize AMD’s role in all of this, the Xbox One features a semi-custom 28nm APU designed with AMD. If this sounds familiar it’s because the strategy is very similar to what Sony employed for the PS4’s silicon.

The phrase semi-custom comes from the fact that AMD is leveraging much of its already developed IP for the SoC. On the CPU front we have two Jaguar compute units, each one with four independent processor cores and a shared 2MB L2 cache. The combination of the two give the Xbox One its 8-core CPU. This is the same basic layout of the PS4‘s SoC.

If you’re not familiar with it, Jaguar is the follow-on to AMD’s Bobcat core - think of it as AMD’s answer to the Intel Atom. Jaguar is a 2-issue OoO architecture, but with roughly 20% higher IPC than Bobcat thanks to a number of tweaks. In ARM terms we’re talking about something that’s faster than a Cortex A15. I expect Jaguar to be close but likely fall behind Intel’s Silvermont, at least at the highest shipping frequencies. Jaguar is the foundation of AMD’s Kabini and Temash APUs, where it will ship first. I’ll have a deeper architectural look at Jaguar later this week. Update: It's live!

Inside the Xbox One, courtesy Wired

There’s no word on clock speed, but Jaguar at 28nm is good for up to 2GHz depending on thermal headroom. Current rumors point to both the PS4 and Xbox One running their Jaguar cores at 1.6GHz, which sounds about right. In terms of TDP, on the CPU side you’re likely looking at 30W with all cores fully loaded.

The move away from PowerPC to 64-bit x86 cores means the One breaks backwards compatibility with all Xbox 360 titles. Microsoft won’t be pursuing any sort of a backwards compatibility strategy, although if a game developer wanted to it could port an older title to the new console. Interestingly enough, the first Xbox was also an x86 design - from a hardware/ISA standpoint the new Xbox One is backwards compatible with its grandfather, although Microsoft would have to enable that as a feature in software - something that’s quite unlikely.

Microsoft Xbox One vs. Sony PlayStation 4 Spec comparison
  Xbox 360 Xbox One PlayStation 4
CPU Cores/Threads 3/6 8/8 8/8
CPU Frequency 3.2GHz 1.6GHz (est) 1.6GHz (est)
CPU µArch IBM PowerPC AMD Jaguar AMD Jaguar
Shared L2 Cache 1MB 2 x 2MB 2 x 2MB
GPU Cores   768 1152
Peak Shader Throughput 0.24 TFLOPS 1.23 TFLOPS 1.84 TFLOPS
Embedded Memory 10MB eDRAM 32MB eSRAM -
Embedded Memory Bandwidth 32GB/s 102GB/s -
System Memory 512MB 1400MHz GDDR3 8GB 2133MHz DDR3 8GB 5500MHz GDDR5
System Memory Bus 128-bits 256-bits 256-bits
System Memory Bandwidth 22.4 GB/s 68.3 GB/s 176.0 GB/s
Manufacturing Process   28nm 28nm

On the graphics side it’s once again obvious that Microsoft and Sony are shopping at the same store as the Xbox One’s SoC integrates an AMD GCN based GPU. Here’s where things start to get a bit controversial. Sony opted for an 18 Compute Unit GCN configuration, totaling 1152 shader processors/cores/ALUs. Microsoft went for a far smaller configuration: 768 (12 CUs).

Microsoft can’t make up the difference in clock speed alone (AMD’s GCN seems to top out around 1GHz on 28nm), and based on current leaks it looks like both MS and Sony are running their GPUs at the same 800MHz clock. The result is a 33% reduction in compute power, from 1.84 TFLOPs in the PS4 to 1.23 TFLOPs in the Xbox One. We’re still talking about over 5x the peak theoretical shader performance of the Xbox 360, likely even more given increases in efficiency thanks to AMD’s scalar GCN architecture (MS quotes up to 8x better GPU performance) - but there’s no escaping the fact that Microsoft has given the Xbox One less GPU hardware than Sony gave the PlayStation 4. Note that unlike the Xbox 360 vs. PS3 era, Sony's hardware advantage here won't need any clever developer work to extract - the architectures are near identical, Sony just has more resources available to use.

Remember all of my talk earlier about a slight pivot in strategy? Microsoft seems to believe that throwing as much power as possible at the next Xbox wasn’t the key to success and its silicon choices reflect that.

Introduction Memory Subsystem


View All Comments

  • elitewolverine - Thursday, May 23, 2013 - link

    its the same gpu at heart, sure shaders are lower, because of eSram. You might want to rethink how internals work. Advantage will be very minimal Reply
  • alex@1234 - Friday, May 24, 2013 - link

    In every place its mentioned 32% higher GPU power, I don't think A GTX 660 TI and GTX 680 are equal. For sure PS4 holds the advantage. Lower shaders and lower in everything compared to PS4, DDR3 Xbox one-PS4 DDR5. For ESRAM, I will tell you something have a SSD, have 32 GB RAM, it cannot make it for a better GPU. Reply
  • cjb110 - Thursday, May 23, 2013 - link

    In some ways this is the opposite to the previous generation. The 360 screamed games (at least its original dashboard), whereas the PS3 had all the potential media support (the xbar interface though let it down) as well as being an excellent blu-ray player (which is the whole reason I got mine).

    This time around MS have gone all out entertainment, that can do games, where as Sony seems to have gone games first. I'm imagining that physically the PS4 is more flashy too like the PS3 and 360 where...game devices not family entertainment boxes.

    Personally I'm keeping the 360 for my games library, and the One will likely replace the PS3.
  • Tuvok86 - Thursday, May 23, 2013 - link

    Xbox One ~ 7770 Ghz
    PS4 ~ 7850
  • jnemesh - Thursday, May 23, 2013 - link

    One of my biggest concerns with the new system is the Kinect requirement. I have my Xbox and other electronics in a rack in the closet. I would need to extend the USB 3.0 (and I am assuming this time around, the Kinect is using a standard USB connector on all models) over 40 feet to get the wire from my closet to the location beneath or above my wall mounted TV. With the existing Kinect for the 360, I never bothered with it, but you COULD buy a fairly expensive USB over cat5 extender (Gefen makes one of the more reliable models, but it's $499!). I know of no such adapter for USB 3.0, and since Kinect HAS to be used for the console to operate, this means I won't be buying an Xbox One! Does anyone know of a product that will extend USB 3.0 over a cat5 or cat6 cable? Or any solution? Reply
  • epobirs - Saturday, May 25, 2013 - link

    There are USB 3.0 over fiber solutions available but frankly, I doubt anyone at MS is losing sleep over those few homes with such odd arrangements. Reply
  • Panzerknacker - Thursday, May 23, 2013 - link

    Is it just me or are these new gen consoles seriously lacking in CPU performance? According to the benchmarks of the A4-5000, of which you could say the consoles have two, the CPU power is not even going to come close to any i5 or maybe even i3 chip.

    Considering the fact they are running the X86 platform this time, which probably is not the most efficient to run games (probably the reason why consoles in the past never used x86), and the fact that they run lots of secondary applications next to the game (which leaves maybe 6/8 cores left for the game on average), I think CPU performance is seriously lacking. CPU intensive games will be a no-no on this next gen on consoles.
  • Th-z - Saturday, May 25, 2013 - link

    The first Xbox used x86 CPU. Cost was the main reason not many consoles used x86 CPU in the past, unlike IBM Power and ARM, x86 doesn't give out license to whatever company to make their own CPU. But this time they probably see benefit has outweighed the cost (or even less cost) with x86 APU design from AMD - good performance per dollar/per watt for both CPU and GPU. I am not sure if Power today can reach this kind of performance per dollar/per watt for a CPU, or ARM has the CPU performance to run high end games. Also bear in mind that consoles use less CPU cycle to run games than PC. Reply
  • hfm - Thursday, May 23, 2013 - link

    "Differences in the memory subsytems also gives us some insight into each approach to the next-gen consoles. Microsoft opted for embedded SRAM + DDR3, while Sony went for a very fast GDDR5 memory interface. Sony’s approach (especially when combined with a beefier GPU) is exactly what you’d build if you wanted to give game developers the fastest hardware. Microsoft’s approach on the other hand looks a little more broad. The Xbox One still gives game developers a significant performance boost over the previous generation, but also attempts to widen the audience for the console."

    I don't quite understand how their choice of memory is going to "widen the audience for the console". Unless it's going to cause the XBox One to truly be cheaper, which I doubt. Or if you are referring to the entire package with Kinect, though it didn't seem so in the context of the statement.
  • FloppySnake - Friday, May 24, 2013 - link

    It's my understanding (following an AMD statement during a phone conference over 8000m announcement) that ZeroCore had been enhanced for graceful fall-back, powering-down individual GPU segments not just the entire GPU. If this is employed we could see the PS4 delivering power as needed (not sure what control they'll have over GDDR5 clocks if any), but potentially not power hungry unless it needs to be. Perhaps warrants further investigation?

    I agree with the article that if used appropriately, the 32MB SRAM buffer could compensate for limited bandwidth, but only in a traditional pipeline; it could severely limit GPGPU potential as there's limited back-and-forth bandwidth between the CPU and GPU, a buffer won't help here.

    For clarity, the new Kinect uses a time-of-flight depth sensor, completely different technology to the previous Kinect. This offers superior depth resolution and fps but the XY resolution is actually something like 500x500 (or some combination that adds up to 250,000 pixels).

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