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
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  • epobirs - Saturday, May 25, 2013 - link

    "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."

    I would disagree. You won't see compatibility with existing Xbox discs but I very much expect a line of original Xbox titles to be offered as download purchases on the new machine. If Nintendo thinks $5 for an NES game running ont he Wii U is reasonable, Microsoft should able to make some good coin on a core set of two or three dozen Xbox titles at $10 each.

    As for the 360 library, those should start turning up in HD (well, HD-ier) remakes in about four years as the market ripens for bringing those item back into circulation. This has worked very well for adding value to the PS3 with HD remake collections of PS2 hits. Given the right tools, reworking old IP can be very cost effective.

    Some of the best original Xbox titles might get native remakes. We've already had Halo Anniversary and I wouldn't be surprised to see a Halo 2 Anniversary turn up for Xbox One. Jade Empire and the Knights of the Old Republic games may be worth the investment.
    Reply
  • RedavutstuvadeR - Saturday, May 25, 2013 - link

    Anand Lal Shimpi why did you not mention any thing about the four move engines in the Xbox one and the capabilities of the cloud quadrupling the Xbox ones power Reply
  • RedavutstuvadeR - Saturday, May 25, 2013 - link

    a link to cloud power of XB1
    news.softpedia.com/news/Xbox-One-Cloud-Makes-the-Console-Four-Times-More-Powerful-355818.shtml
    Reply
  • tipoo - Monday, May 27, 2013 - link

    iirc the PS4 had similar hardware blocks to the Move engines, just no fancy branding? And the cloud compute thing is a future theoretical, I'll factor it in when it's actually shown to work well. It can't be used for any latency sensitive calculations of course. Reply
  • slickr - Saturday, May 25, 2013 - link

    http://i.imgur.com/5WXh32l.jpg Reply
  • jmr99 - Saturday, May 25, 2013 - link

    The Xbox 1 (aka PS4 Mini aka PS4 Lite) sure is a colossal disappointment. Microsoft are trying to cut costs and save money in order to create the biggest gap they can btwn selling price and production cost. In other words, the Apple approach: rape your customers. Kudos to Sony for 1152 cores and gddr5. Reply
  • croc123 - Sunday, May 26, 2013 - link

    Interesting article in my 'local' rag this AM...

    http://www.smh.com.au/digital-life/games/how-micro...
    Reply
  • JimF2 - Wednesday, May 29, 2013 - link

    I won't buy any console that needs an internet connection. It is a huge privacy risk to have a console with a camera that connects to the internet. A console that connects to the internet once per day or once per week has the same privacy risk as a console with an always-on connection.

    Gamers should boycott Xbox One so the console manufacturers get the message that we won't accept a required internet connection. If a physical disk is inserted in the console, no internet connection should be needed to prevent piracy. The console manufacturers just have to develop a proprietary disk format that can't be copied by Windows, Mac or Linux. It would be fine if gamers who don't want to put a physical disk in the console to prove they own the game are required to have an internet connection. That way, if a gamer wants to prevent game companies from spying on them, they would just swap disks when switching games. If a gamer uses LIVE or they want the convenience of not needing to swap disks, they would provide an internet connection.
    Reply
  • TheEvilBlight - Wednesday, May 29, 2013 - link

    The PS4's PS3 games are allegedly coming via GaiKai. I'm curious what MS will do for the old stable of games. I wonder if it would be too much to implement other VM's for the Xbox and the Xbox 360; though a VM on an x86 running PPC is likely to suffer severe penalties. It's either state or gaming from the cloud.

    Alternatively, developers will recompile some of the "best hits" on the 360 and re-release for the Xbox One. I wonder how that would work with the Halo series, but having Gears of War on a faster machine might be fun.
    Reply
  • Thermalzeal - Wednesday, May 29, 2013 - link

    Anand, any information on whether the Xbox One will utilize HMA (Hybrid Memory Access) in comparison to the PS4? Reply

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