The Xbox One: Hardware Analysis & Comparison to PlayStation 4
by Anand Lal Shimpi on May 22, 2013 8:00 AM ESTMemory Subsystem
With the same underlying CPU and GPU architectures, porting games between the two should be much easier than ever before. Making the situation even better is the fact that both systems ship with 8GB of total system memory and Blu-ray disc support. Game developers can look forward to the same amount of storage per disc, and relatively similar amounts of storage in main memory. That’s the good news.
The bad news is the two wildly different approaches to memory subsystems. Sony’s approach with the PS4 SoC was to use a 256-bit wide GDDR5 memory interface running somewhere around a 5.5GHz datarate, delivering peak memory bandwidth of 176GB/s. That’s roughly the amount of memory bandwidth we’ve come to expect from a $300 GPU, and great news for the console.
Xbox One Motherboard, courtesy Wired
Die size dictates memory interface width, so the 256-bit interface remains but Microsoft chose to go for DDR3 memory instead. A look at Wired’s excellent high-res teardown photo of the motherboard reveals Micron DDR3-2133 DRAM on board (16 x 16-bit DDR3 devices to be exact). A little math gives us 68.3GB/s of bandwidth to system memory.
To make up for the gap, Microsoft added embedded SRAM on die (not eDRAM, less area efficient but lower latency and doesn't need refreshing). All information points to 32MB of 6T-SRAM, or roughly 1.6 billion transistors for this memory. It’s not immediately clear whether or not this is a true cache or software managed memory. I’d hope for the former but it’s quite possible that it isn’t. At 32MB the ESRAM is more than enough for frame buffer storage, indicating that Microsoft expects developers to use it to offload requests from the system memory bus. Game console makers (Microsoft included) have often used large high speed memories to get around memory bandwidth limitations, so this is no different. Although 32MB doesn’t sound like much, if it is indeed used as a cache (with the frame buffer kept in main memory) it’s actually enough to have a substantial hit rate in current workloads (although there’s not much room for growth).
Vgleaks has a wealth of info, likely supplied from game developers with direct access to Xbox One specs, that looks to be very accurate at this point. According to their data, there’s roughly 50GB/s of bandwidth in each direction to the SoC’s embedded SRAM (102GB/s total bandwidth). The combination of the two plus the CPU-GPU connection at 30GB/s is how Microsoft arrives at its 200GB/s bandwidth figure, although in reality that’s not how any of this works. If it’s used as a cache, the embedded SRAM should significantly cut down on GPU memory bandwidth requests which will give the GPU much more bandwidth than the 256-bit DDR3-2133 memory interface would otherwise imply. Depending on how the eSRAM is managed, it’s very possible that the Xbox One could have comparable effective memory bandwidth to the PlayStation 4. If the eSRAM isn’t managed as a cache however, this all gets much more complicated.
| Microsoft Xbox One vs. Sony PlayStation 4 Memory Subsystem Comparison | ||||||||||||||
| Xbox 360 | Xbox One | PlayStation 4 | ||||||||||||
| 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 | |||||||||||
There are merits to both approaches. Sony has the most present-day-GPU-centric approach to its memory subsystem: give the GPU a wide and fast GDDR5 interface and call it a day. It’s well understood and simple to manage. The downsides? High speed GDDR5 isn’t the most power efficient, and Sony is now married to a more costly memory technology for the life of the PlayStation 4.
Microsoft’s approach leaves some questions about implementation, and is potentially more complex to deal with depending on that implementation. Microsoft specifically called out its 8GB of memory as being “power friendly”, a nod to the lower power operation of DDR3-2133 compared to 5.5GHz GDDR5 used in the PS4. There are also cost benefits. DDR3 is presently cheaper than GDDR5 and that gap should remain over time (although 2133MHz DDR3 is by no means the cheapest available). The 32MB of embedded SRAM is costly, but SRAM scales well with smaller processes. Microsoft probably figures it can significantly cut down the die area of the eSRAM at 20nm and by 14/16nm it shouldn’t be a problem at all.
Even if Microsoft can’t deliver the same effective memory bandwidth as Sony, it also has fewer GPU execution resources - it’s entirely possible that the Xbox One’s memory bandwidth demands will be inherently lower to begin with.
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Krysto - Wednesday, May 22, 2013 - link
Seems like Sony has a winner here in terms of hardware and developer support, too.Any idea if PS4 does indeed use the full OpenGL 4.3 as rumored? And is it based on some custom Linux OS?
powerarmour - Wednesday, May 22, 2013 - link
PS4 will likely run some form of libGCM similar to the PS3, this is another area the PS4 may easily have the upper hand in, software overheads...Death666Angel - Wednesday, May 22, 2013 - link
All pretty much expected on the hardware side of things. And I like it as well, as a non-console gamer (I bought an Xbox 360 for the Kinect to introduce my wife and larger family to gaming... it's mostly left unused, since our living room is on the small side and we need to rearrange a lot to play). The current high end PC should be able to run all the games developed for the consoles very well, which is good. There is less chance of getting rubbish ports since all 3 consoles are so similar. All positives for me as a PC gamer.For the software/entertainment side, that doesn't interest me in the least. The Xbox could never be my media hub because I have an A/V receiver for that, as I expect many people do. And all the software stuff, streaming etc. I have my doubts about everything trickling down to the German market as they envision it. Plus, I'm not a TV guy or a rent guy. I like to own my stuff as much as possible.
Silma - Wednesday, May 22, 2013 - link
It seems to me that the Microsoft approach is Superior to the Sony one if One + Kinnect is priced competitively or at not too big a premium with the PS4.Sony has a history of hacker-friendly internet platforms and it is often in denial. Would I trust the Playstation Network? No way.
If consoles become the center of the TV/Entertainment center, if people will really use the console as a Skype terminal or as today use the Kinnect to excercise then I think the Microsoft offering is the more attractive one and that its features will interest buyers more than to know that one console has more shader units than the other.
In addition, it would not be difficult for Microsoft to extend the Platform with byod features such as Skydrive access, Office 365 and so forth.
jonjonjonj - Wednesday, May 22, 2013 - link
this annoys the hell out of me. who cares about power. i want performance. i want my console or pc so power hungry it trips a breaker. its obvious everyone wants a kinect instead of a better gpu. right? tv on xbox is useless. so i dont have to hit the input button on my remote? seriously? its not like you get the service from ms. you have to pay for xbox live gold and be a paying cable customer. it offers absolutely nothing. i have 2 360's but i have no plan on my buying this garbage cable box i already have a dvr. ill take that $500+ and buy a 27" 1440p monitor and another video card for sli. ms already proved to me over the past 3 years they don't care about the core gamers anymore and this just reaffirms it. i hope this console fails so miserably.elitewolverine - Thursday, May 23, 2013 - link
because everyone wants a ps4eyetoy in their ps4 right? instead of a better gpu right?Oh wait...ps4 did the same thing.
Everyone wants a camera with their laptop instead of a better cpu/gpu right? Oh wait...
In my house hold finding the remote is an issue. Not because we forget but with 8 people in a home, each one grabbing at it at different times, this becomes an issue.
You have a dvr? great, the xbox is not designed to replace it, in fact its already stated its working along side....any cable box.
Why do people pay for TiVo? there is a service to be had, and its much better imo than comcasts dvr or the offering by Direct. I was skeptical about TiVo till my damn ex got me hooked on it.
Not to mention how many times I have to tell my parents the channels of anything other than local news. Now they just have to say...hgtv, animal, history. They don't live with me, but they will be getting one. This is also a plus for me, as my kids don't have to worry about memorizing the channels, even though they do currently.
Your mentality is what the losers of the tablet wars are facing...
Why would people want a tablet? I have a laptop, pc, tv, ipod...the list goes on...
Convenience and easy. This is what x1 is offering, along with cloud computing, dedicated servers, and games games games games
jonjonjonj - Tuesday, June 4, 2013 - link
really? sony hasn't announced the pseye is going to be bundled with all ps4's. in fact there are links to sony videos that say "Playstation4 camera may be required and is sold separately". even if it is the ps4 has a 30% faster gpu then xbox so ms should have spent that kinect money on making the gpu more competitive. the 360 already showed kinect was a failure for gaming. unless you are a girl who wants to play dance central there is no reason to get a kinect. this is why bundling the kinect boggles my mind. it shows me ms either doesn't get it or doesn't care if the xbox is a gaming console.the best defense of xbox tv you can come up with is you constantly loose your remote? my remote is always in the room with the tv. not very hard to find.
i know its not going to replace my dvr. that doesn't change the fact that i see zero benefit to using xbox and i still have to pay for my dvr. i forgot you can use voice commands and wave your hands around like an idiot. no thanks ill pass and stick to my remote.
"games games games games"? i must have missed that part of the conference. when they announce their exclusives at e3 expect them to mostly be kinect and XBLA games not the non kinect AAA games everyone wants. just like they have over the last 3 years.
i have a ipad and never use it. the only thing its good for is quickly checking email or watching a youtube video. beyond that my laptop or desktop is 10x faster and easier to use. people are buying tablets because it the cool thing to do and everyone already has multiple pc's and laptops. once everyone has a tablet sales will slow down.
BPB - Wednesday, May 22, 2013 - link
It appears MS has dumped the WMC extender abilities. It's not a surprise, but I don't give two hoots about the DVR overlay. With my HTPC and extenders I save a lot of money not having a DVR. MS wants me to go back to a DVR, and I won't. Given all else it looks like PS4 for me with continued 360 gaming (which MS said will also get updated in some sort of way, won't know till E3 what that means). But pricing and other factors will be part of that equation too.elitewolverine - Thursday, May 23, 2013 - link
im surprised you hooked up an htpc, considering you have a hard time understanding works along side your cable/dvr via infared. Meaning when you tell it to change the channel it will do so, at your cable box/dvr/htpc. I can understand how something so simple can be confusing...BPB - Monday, May 27, 2013 - link
Wow, can't wait till I'm all growed up like you! Then I too can be a jackass.I watched the MS presentation live, and have followed many of the MS follow-up discussions about Xbox One. They've mentioned working with cable companies like Comcast for TV overlay, but oddly enough they haven't mentioned working with HTPC's running their own Windows software. Then again maybe they too have a hard time figuring all this out. Please post your phone number or email so MS can contact you and you can set them straight.