Microsoft confirms: Xbox One OS uses 3GB RAM, 5GB RAM for games

In a long interview today Marc Whitten of Microsoft confirmed how much of the Xbox One’s 8GB RAM will be taken up by the OS and games. He did this indirectly by not denying past rumors of the RAM being broken down this way. He was directly asked if 3GB RAM was used for the OS and he shyed away from answering, hinting that it may be true. In addition to that, Kotaku has reported that the OS uses 2 CPU cores, 3GB RAM AND 10% of the GPU.

It has been rumored for months now that the OS for the new Xbox would use 3GB RAM and Whitten confirmed in this interview that it will require “around” 3GB. So it could be a bit more, could be a little bit less. This leaves about 5GB RAM for game developers.

That is considerably less than what is expected from the PS4. Sony’s next console is expected to only need 1GB for its OS, though that could always change.

5GB of RAM for developers isn’t something to scoff at though. Even if the Xbox One isn’t rocking the 8GB GDDR5 memory like the PS4, it still isn’t a slouch. There is no doubt that a good part of that 3GB OS RAM is taken up by the console’s ability to multi-task and suspend applications on the fly. The transition process between film, tv, and games was almost instant. That’s sure to require a fair amount of memory.

UPDATE: A lot of people have been questioning whether Marc Whitten not outright denying things like 5GB RAM is really “confirming” indirectly. I understand this concern. Over the past week or so, multiple developers have cited that they’re fine with using the Xbox One’s 5GB game RAM, like Avalanche Studios, makers of Just Cause.

25 Comments on Microsoft confirms: Xbox One OS uses 3GB RAM, 5GB RAM for games

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  2. erale

    So when exactly was this confirmed in the video? I just heard “My impression is that the OS uses 3GB of RAM” from the GI guy…

    • christrules0041

      He didn’t deny it but said I think we have a well rounded system which implys that yeah there is somewhere close to 3GB of RAM having to be used for OS. Of coarse he won’t go out and say yeah we have a technical disadvantage from Sony. It would be digging there own grave

    • tariban

      There is a G in GDDR5 for a reason. It is a spec that is heavily biased towards GPUs due to the very wide memory interface. In order to have this wide memory interface, compromises had to made that caused the latency to shoot up (several hundred cycles) to the point where it’s a pretty bad idea to use it for CPUs.

      What does this mean? 170GB/s is a bogus number. In reality applications will rarely see speeds getting anywhere near this high.

      eSRAM generally has a latency of a dozen or so cycles which is orders of magnitude faster than GDDR5 (and DDR3, for that matter). DDR3’s latency is also much lower than GDDR5’s. Lower latency means less stalling. Taking this into account the XBone shader units will likely see considerably more utilisation than the PS4’s, so the fact that is has two thirds of the units is not really an issue.

      Also, I wouldn’t really call this a confirmation at all. It’s still all guess work atm.

      • p3ngwin

        i don’t think you know as much about RAM-types and processing as
        the you believe you do.

        latencies are less important than bandwidth in a videogame console, nobody is running general processing tasks like office suites and, etc on consoles. the console is a dedicated piece of technology for games and TV at best, which is mostly parallel processing intensive.

        GDDR is not a compromise in so much as it’s a “better fit” for consoles.

        Consoles are not general purpose CPU machines these days, they’re GPU machines with compute processing in massively parallel loads. the CPU is practically a “delegator” or a “task manager” as has been demonstrated with the PS3’s CELL main processor and SPE’s.

        This is why AMD and Intel are investing in massively parallel architectures, from AMD using their GPU’s to replace the traditional FPU and Intel using “Larrabee-based” Xeon Phi for the next evolution of the traditional CPU.

        Even Nvidia are placing ARM processors on their Tesla GPU’s for massively parallel processing that are practically “compute clusters on a card”.

        Even Tim Sweeny of Epic foresaw the evolution of CPU’s becoming massively parallel back in 2007:

        “I think CPU’s and GPU’s are actually going to converge 10 years or so down the road. On the GPU side, you’re seeing a slow march towards computational completeness. Once they achieve that, you’ll see certain CPU algorithms that are amicable to highly parallel operations on largely constant datasets move to the GPU. On the other hand, the trend in CPU’s is towards SMT/Hyperthreading and multi-core. The real difference then isn’t in their capabilities, but their performance characteristics.”

        the future is massively parallel, and that means a traditional CPU with low-latency access for general serial tasks is becoming irrelevant.

        lower latencies are better when you’re processing general CPU-like tasks, but as this is a game console GPU-like processing requires more bandwidth than latency-sensitive memory.

        the AMD APU’s used in the Xbox-One and PS4 are bandwidth-sensitive, not latency-sensitive, so the GDDR is a much more appropriate match for a game console than any latency benefits from DDR.

        the multiple buses from CPU-GPU benefit from massive bandwidth to the main RAM pool, and latency has little to do with a games console processing compared to raw bandwidth. Everything from the graphics pipeline, to AI, post-processing, physics, are all done on the GPU’s shaders, and all require bandwidth more than latency.

        the parallel nature of the GPU architecture and the compute-heavy nature of these consoles mean bandwidth is king, not latency.

        the parallel nature of graphics calls for input and output from vRAM at many points covering many concurrent streams of data. Some of that vRAM is also subdivided into memory buffers and caches to save data that would otherwise have to re-compiled for following frames.

        All this swapping out of data calls for high bandwidth, but latency can be lax (saving power demand) as any stall in one thread is generally lost in the sheer number of threads queued at any given time.

        Those are massively parallel simultaneous threads requiring better bandwidth, not better latency.

        GDDR5 *simultaneously* allows a write *and* read to/from memory every clock cycle, whereas DDR3 is limited to a read *or* a write, which reduces bandwidth. GDDR also allows for multiple memory controllers to cope with the I/O functions.

        Xbox decided to go with embedded RAM on the GPU-side to compensate for the lack of overall memory bandwidth for the system memory, similar to the last Xbox design. this is a small memory pool that can only be used in very limited ways, compared to the general “complete” system RAM the PS4 uses where ALL the 8GB of RAM is fast with high bandwidth.

        170GB/s is not a “bogus number”, it is a factual specification of the memory used and the nature of the memory type.

        it doesn’t matter that the Xbox One has lower latency, because it won’t have as much bandwidth as the GDDR flooding the PS4’s processors. Any latency difference in the PS4 will be completely negated by the sheer number of parallel threads.

        you may not believe the specs, but then you’d be ignorant of the developers who applaud the specs, and the creator of the architecture himself, Mark Cerny who designed the specs.

        176GB/s is not a “bogus number”, the only thing bogus is the presumption you know what you’re talking about.

        the Xbox One has much few GPU shaders to do that processing anyway, so it’s another reason the Xbox One is inferior. Less bandwidth + fewer shaders = less performance.

        If you don’t understand the difference between DDR and GDDR then maybe you shouldn’t be discussing it with false authority.

        • leozno1

          So you’re saying that latency doesn’t play a role when the game has to switch over and load a cut-scene? Or has to load a new section of a map in an open world game? To think that latency comes second to pure bandwidth is ludicrous.

          Think of mobile phone networks for a second. If you are going to load a webpage on your phone, 1 network provides speeds of 5mbps and a latency of 50ms and the other network provides speeds of 15 mbps and latency of 500 ms, which page is going to load faster?

          • p3ngwin

            i said in a games console bandwidth is more important than the increased latency of GDDR5 v’s DDR3.

            Latency becomes less relevant when the sheer number of parallel threads is in effect.

            if you think latency is more important to a games console, you are mistaken. Just think of the PS4’s creator, Mark Cerny, and even the developers who applaud the design (as i linked above), who all agree with bandwidth being king.

            If you think you know better, maybe you should contact them and let them know they are wrong to prioritize bandwidth, i’m sure they’d love to hear the reasons why you think their priorities are “ludicrous”.

            You’re analogy of games consoles being remotely like web browsing on mobile networks is irrelevant. The 5Mb/s datastream is still 5Mb/s, regardless of latency, but the other 15Mb/s stream has a much higher throughput flowing to the more powerful GPU processor.

            To use your own analogy: would you rather try and stream a 1920×1080 youtube video on your 5Mb/s connection or use a 15Mb/s one ?

            What quality will 5Mb/s afford you ?

            here, have a look at the irrelevant difference such latency makes in gaming, knock yourself out learning bandwidth is better:




            so there you go, bandwidth beats latency for a games console.

          • Davie Culpepper

            Depends on how you system is set up!Both the Xbox One and PS4 both have some bennifits for their system structure!

            One thing you can not do is over look the importance of data move engines,encoder engines,shape engine,video codec engines and top if that the esram!

            I believe now both systems are down to a reserve of ram to 2 gigs each!

          • p3ngwin

            Both systems have desperate processors for encoding and decoding, both for audio and video, even data steaming.

            I have no idea why you believe both systems are “down to 2gb of RAM”.

            Do you have some information to share to support such a claim?

          • Nate

            Your right. Graphics needs faster ram in order to do be faster. Look at the apu by amd. Its limited to ddr3 which is a lot slower than GDDr5 which is graphics memory. The graphics chip in the consoles is in all relevant circumstances an apu so by using faster memory the ps4 is able to run games much better in comparison to ddr3.

      • B_Boss

        So its your word/theory against Mark Cerny’s facts, lead architect of the PS4? How about “no”.

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  5. Miridius

    What kind of bullshit article is this? First you say “confirms”, then you say it’s only “indirectly”, then you say actually all he did was refuse to answer the question. Either make up your fucking mind, or go learn the meaning of the word “confirms”

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  7. Noah

    “He did this indirectly by not denying past rumors of the RAM being broken down this way. He was directly asked if 3GB RAM was used for the OS and he shyed away from answering, hinting that it may be true.”


  8. james braselton

    hi there coretion xbox one uses 3 os 3 os 3 gb a piece is 9 gb toatal and microsoft says only 8 gb ram soo toatal ram is minus 1 gb or -1 gb soo how dose a game console have negative gb of ram

    • gimmegimmekevin

      No, it has been reported (and not denied by MS and confirmed by developers that the 3 layered OS takes up 3GB RAM total, leaving 5GB left of that 8GB for games.

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  11. Benjamin Anson ツ

    Sony have just confirmed that the PS4 uses 5.5GB of RAM for gaming. So if this article is true the PS4 only has 512MB more RAM used for games. I my opinion, it’s not really a difference.

    I’m really looking forward to the next gen and hope everyone is happy with their choice! 😀

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