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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  • Majeed Belle - Sunday, September 08, 2013 - link

    I don't think it will be just exclusives perse. If we think about what types of games both systems will get then we will see likely see better performance on the PS4 for games that are graphic intensive.

    Think about RTSs for example that tend to have tons of stuff happening on screen or something like Dungeon Defenders.

    Skyrim, Dragon's Age, Dragon's Dogma etc also all have tons of lighting and graphical effects going on at the same time that should see benefits from the difference in ram.

    Anyone who has played Dragon's Dogma on the PS3 and uses a Mystic Knight with 3 great cannons firing all at the same time has seen slowdown happen and that's because of the lower amount of ram. This should be a problem with the PS4.
    Reply
  • Majeed Belle - Sunday, September 08, 2013 - link

    -edit
    This SHOULDN'T be a problem with the PS4
    Reply
  • jeffkibuule - Wednesday, May 22, 2013 - link

    "Why didn't they just match X?" Because the design of these chips to have them tested, validated, and shipping on time is on the order of years, not weeks. Reply
  • dysonlu - Wednesday, May 22, 2013 - link

    "Finish off Sony" is a big overstatement considering that PS3 surpassed Xbox360 in some recent reports. Reply
  • FearfulSPARTAN - Wednesday, May 22, 2013 - link

    I hate it when websites get info wrong or interpret it badly, sony matched shipped numbers not sales numbers. I fyou go to vgchartz you will see the xbox was still up around a million units last time I checked. Reply
  • blacks329 - Wednesday, May 22, 2013 - link

    I think when both systems are hovering around the same numbers and are off by 1 million. It's fairly negligible in the grand schemes of things. It's impressive for Sony how close they are, considering how colossally Sony screwed up early in this gen and started a year after the 360. Reply
  • beuwolf - Wednesday, May 22, 2013 - link

    You checked a long time ago then: http://www.vgchartz.com/ - they are equal. And that's despite Xbox having 1 extra year...

    If you look at the global year to date, then PS3 is outselling 360 by more than a million this last year.
    Reply
  • c1979h - Thursday, May 23, 2013 - link

    Kind of sorry for Sony, it took them that long to get even, remember they had Asia all to themselves. It also happens to be the biggest continent in the world. Reply
  • blacks329 - Thursday, May 23, 2013 - link

    Biggest continent in the world doesn't mean anything. Their purchasing power pales in comparison to the US and Europe.

    Although their purchasing power is increasing, which is more beneficial for Sony in the long term, but even then it still pales in comparison to what the average North American can purchase.
    Reply
  • xaml - Thursday, May 23, 2013 - link

    If every third Xbox 360 user had to get at least one repaired and after that died, bought a new one until finally salvaged by the 'Slim'... Reply

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