Mark Cerny Explains How the PS4′s 8 GB GDRR5 RAM and Bus Work and Why They Were Chosen

The PS4′s loving dad (or at least one of its fathers) Mark Cerny did a lot of thinking on the console’s architecture even before the first piece of circuitry was printed, so he's the best one to explain how the much touted 8 gigabytes of unified GDRR5 RAM coupled with the bus work, and why that solution was implemented.

[PositiveEmotions]

Why doesnt n4g just makes one article telling everything that mark cerny explain instead having so many articles on mark cerny explained this and that..

No offense n4g

[Prcko]

mostly site editors make stories on their websites,and they submit those stories here for hot temperature
after few weeks i kinda know those websites:
dualshockers,playstationlifes tyle,dso gaming,gamechup and few others :)

[black0o]

just watch it ur self .. he's great

http://www.youtube.com/watc...

[cayleee]

No offence but why doesnt Mark Cerny ever talk about the CPU, which happens to be a tablet CPU running at 1.6ghz or whatever it is?

Or why not mention the mobile GPU within the machine. Why focus on something like RAM which essentially does no calculations. Its just a container that holds Data and transports it. How fast that Data gets processed essentially depends on CPU & GPU funnily both of those are never talked about.

[CryofSilence]

@Cayleee

The modified Jaguar AMD CPU is a desktop based, x86 8 core CPU. Tablets generally use ARM based chips. Point one: invalidated.

The GPU outperforms in specs capable desktop GPUs. Point two: invalidated.

RAM is the highway on which calculations are transferred. Increase the number of lanes and the speed limit, and you get better results. The processors will have no problems filling that; most current processors wouldn't have problems either. Point three: invalidated.

Stop trolling and read a little.

[loulou]

caylee becareful. you cannot say things like that on n4g.

have a look at crysis 3 or bf3/4 recommended ultra settings, and you will see that the amount of RAM is not huge at all.

it is the cpu and gpu that make the difference.

but dont bother trying to say that on here. they dont want to hear things like this. all of a sudden ram is the new buzzword, just like cell was back in the day.

and yes kids i have a ps4 on pre-order

[arjman]

@loulou
Stop turning it into a fanboy-related comment, cayleee stated that the CPU is a tablet processor when in reality the 8-core X86 processor will outperform any ARM processor on the market.

Cayleee if you're gonna troll at least do it properly. If you were an XBox fan you'd know the CPUs in both consoles are very similar and if you were a PC fan you'd know that the 8-core APU isn't comparable to a mobile part. So I ask, what the hell is your deal?

[awi5951]

@arjman

In reality all amd 8 core cpus suck major (&*)&*. Except maybe the 8350 and 8320 and these cpu's in these consoles arent those so its a huge fail on both microsoft and sony's consoles. Console guys should really stop talking like they know anything about pc parts.

I dont think the parts in these consoles are even worth 400 and 500 dollars i think they both are pulling a apple and trying to make major profit off the consoles day one. Because both these consoles sound like gaming Laptops. My Pc far outperforms every card in the 7000 series of amd cards except a 7990 which is a 800 dollar card and these cards dont come close.

So ill just stick to my pc and still have better looking games. I get 110 fps in BF3 on ultra at 1080P right now. Ill put my Pc performance on BF4 against both these consoles and i bet ill still come ontop with fPS performance and graphcis.

[starchild]

@arjman

Actually the AMD CPU in the PS4 and Xbox One utilizes their Jaguar core, which also powers their Kaveri APU, which IS in fact designed for use in tablets and netbooks.

Jaguar has about one quarter the performance per core as an i5 2500k.

[arjman]

@awi5951
Its hard to gauge the true performance of a CPU & GPU combo without truly optimising a game for the hardware. Yes the comparable AMD parts will lose in PC game benchmarks and general benchmarks compared to high end parts but that's because the consoles need low power, low heat components.

With proper optimisation we'll see just how capable these consoles are. I too game on PC and I can appreciate the heat and power specs they have to meet. There's no point comparing the consoles to an i5 and titan equipped PC which most likely has several fans cooling it while it sucks up several hundred watts because they can't get that kind of power in a console sized case.

And I don't appreciate the way you talked up your own PC bragging about it and such, all you're doing is giving PC gamers a bad name.

@star child
The key word is 'utilizes', Nvidia utilize their desktop architecture in their mobile parts for example.

[awi5951]

@arjman

Don't patronize me man the PS fanboys have gone completely mental lately talking about how the PS4 is so much better than the average pc's we game on. Go talk to them about how they are acting. Im just setting the record straight the specs they tout so much pc cards had those specs 3 years ago well actually they were higher.

[Abriael]

Because it would be an enormous wall of text that would bore most people after the first two pages, while it's a lot easier on the eyes and on the brain to read on specific topics, that are of interest and relevant on their own.

[PositiveEmotions]

Ok that makes sense lol

[TechnicianTed]

No Abriael, it's so sites can make more than one article based on one interview. Let's not make it out to be more than it is.

This is what I hate about so called journalism from many of the two bit sites we now get flooded with.

No real journalism, just picking through the bones and getting hits based on headlines.

[Abriael]

@TechnicianTed: if you're not interested, you're entirely free not to read it.

This kind of thing is relevant, whether you like it or not, so I'm not exactly sure why we should omit it to make you happy.

There's very little "bone picking" here, considering that it's the first time the founding architecture of the console has been really explained in detail.

Maybe you should just bring your rage elsewhere?

besides, you don't even know what we're talking about, since this isn't an interview, but a 50 minute conference, so maybe you should get your facts straight?

And it's a very intense conference with a ton of relevant info.
Good luck putting that all in a single article without boring the hell out of your readers.

[TechnicianTed]

'@TechnicianTed: if you're not interested, you're entirely free not to read it. '

I didn't.

'This kind of thing is relevant, whether you like it or not, so I'm not exactly sure why we should omit it to make you happy. '

It's been covered already, it's old news.

'There's very little "bone picking" here, considering that it's the first time the founding architecture of the console has been really explained in detail. '

Explained by the man himself, in the full conference, in better detail than the article.

'Maybe you should just bring your rage elsewhere? '

I haven't got any rage, maybe you have because I insulted your website?

'besides, you don't even know what we're talking about, since this isn't an interview, but a 50 minute conference, so maybe you should get your facts straight?'

I was talking in general. Many websites, including your own, pick through an interview, or in this case a speech given by a developer, and make an article based on a certain passage in that interview, or speech, and make an article on it. Are you denying that is not what this article is?

This very article is based on a small amount of what the full speech amounted to. I'm sorry but we already know, it's not news. It's picking out of the bones and making out that you did all the work.

You did nothing, there's no journalism here. No one on your site has made any real effort with this article. This is something that anyone on the internet could do, it involves no skill whatsoever.

'Good luck putting that all in a single article without boring the hell out of your readers. '

Maybe if your staff had some talent it wouldn't be an issue. If your site actually provided some real journalism I wouldn't be saying what I'm saying.

But your site is one of those two bit sites, so I suppose the truth hurts.

[mrmarx]

more clicks.. more money

[fr0sty]

@ted

You didn't even read the article, which proves you are just talking out of your ass. If you were a real journalist, you would know that keeping your readers engaged and interested is a very big part of it. Presenting them with a 5 page wall of text is not going to keep them reading, and many important details will get lost in the mix. By breaking the story down into individual elements, it allows the journalist to elaborate in much more detail about what was said instead of just a passive mention about it. It allows for deep technical analysis, rather than just bullet point mentions. That's how you properly cover a story without turning it into a novel.

It took 50 minutes just for Cerny to say these things. As a journalist, I wouldn't just cover what he said alone. I would know that my readers may not even understand what the hell he is talking about, so I would do my best to break the technical babble down into layman's terms so everyone could have a grasp on what was being said. I would explain in detail how every bit of what he was talking about worked. By doing so, it would take what took someone 50 minutes to say and turn it into what would take 5 hours to read. Not good for an internet article, so therefore it would have to be broken up.

[nix]

should have just posted the 45 minute long video and the highlights.

[mushroomwig]

How else are they supposed to milk those hits?

[mrmarx]

lol you almost said "tits"

[a_squirrel]

They are the tits of the industry, and they have been swelling with milk since E3.

[adorie]

All aboard the 256 bit bus.

[starchild]

I think Sony were very smart in their designing of the PS4. The x86 ISA and the overall familiar PC-like architecture is going to be great for ease of development.

It's interesting to me to compare to my HD 7950 graphics card in my PC which is based on the same AMD GCN architecture.

The Xbox One has 12 compute units, the PS4 has 18, and my HD 7950 has 28. And instead of a 256 bit bus, the HD 7950 has a 384 bit bus.

[fr0sty]

I would expect similar performance out of PS4 than what you get out of your GPU. Mainly due to not having OS overhead (PS4's OS runs on a small chunk of RAM and even has it's own ARM sub-CPU so the main system CPU doesn't have to process any OS commands at all), the developers are able to have much finer control over the hardware rather than having to work with restrictive APUs, and your PC GPU lacks a few advantages such as being able to issue 64 compute commands at once or having a direct bus connecting the CPU to the GPU. Your CPU and GPU are connected with one PCI express bus, so there is a bandwidth advantage on PS4 due to both chips being on the same die. Also, due to having one pool of RAM, if the GPU wants to help the CPU (or vice versa), they don't have to wait the amount of time it takes to copy that data into their local pool of RAM before they can begin working on it.

This can be made up for somewhat due to the fact that you have more raw power in your CPU and GPU, but your system is only as fast as it's slowest component. PS4 is a finely tuned gaming machine. More so than any PC is for the reasons listed above (and more, I didn't even list all of the customizations made to PS4's GPU).

So, once you balance all that out, you'll very likely end up with similar performance out of the two. You may get a slightly higher framerate out of the PC in certain titles, but I wouldn't expect much more.

[a_squirrel]

My city has 40 buses

[Valkyre]

@ WeMilk

your buses are not enough to display grand theft auto V upon release, they were never interesting enough for red dead redemtpion, the Last of Us dont like your buses either, Metal Gear Solid V "might" at some point enjoy your buses etc etc etc

I believe you get the point...

Enjoy your buses and your limited library of games. Maybe one day you will realise tht your PC has nothing exclusive to it and all those years your buses are essentially inactive because all you do is play console ports with a few texture and resolution upgrades.

But hey,.. good times!

Now that new generation consoles are out, perhaps your buses will actually start working... but i dont want to burst your bubbles... you probably are going to need to upgrade your hardware... :(

[AndrewLB]

People don't seem to realize that memory bandwidth is not some kind of game changer considering the PS4's GPU will never come close to utilizing it all. A great example was inadvertently made by starchild with his HD 7950. That card with it's 384-bit memory bus has a bandwidth of 240gb/s, a texture fillrate of 89.6GTexels/s, and pixel fillrate of 25.6GPixels/s. In contrast, the GTX 680 which by all accounts completely destroys the 7950 has only a 256-bit bus and bandwidth of 192gb/s, while having a texture fillrate of 144.8GTexels/s and pixel fillrate of 36.2GPixels/s.
This proves that memory bandwidth is only useful if the GPU is powerful enough to use it, and much of the HD 7950's massive bandwidth is never utilized, and goes to waste.

Btw... the graphics card that is much closer in performance to the PS4 would be the HD7850. The memory bandwidth and 1.7TFlops are very close to the PS4.

Frosty- Again you equate higher free memory bandwidth with actual performance, but that doesn't change the fact that his card can process 2.9Tflops while the PS4 is at 1.7Tflops, not counting the fact that the HD 7950 has almost DOUBLE the PS4's texture fill rate. Additionally, the OS overhead PC's have to deal with because of windows almost completely falls on the CPU, and not the GPU. When a full screen game is run, GPU's switch to a kind of exclusivity mode which allows the GPU to have almost complete focus on the game itself, but it's the CPU that has to not only run the game, but everything windows related in the background.

[cayleee]

@Valkyre

"Enjoy your buses and your limited library of games."

Isnt it funny but on the contrary its the PS4 that will be having no BC, and will launch with a handful of games. Meanwhile PC has over 25 years of BC covering about every genre out there. Not only that it can emulate any console ever released (outside of PS3 and Xbox 360).

[bumnut]

You do know that a 256 bit bus is mid range at best....... don't you?

[thehitman]

@ positive

Thats because N4G doesnt make articles gaming sites make articles and users submit articles they find to N4G. N4G has no control on the information thats submitted other than the rules and guide lines they have in place.

What is a bigger problem is that 1 site will have a lengthy interview with a said person. Then other sites will make articles with small quotes from that site creating many articles. It floods the news channels and usually text gets taken out of context. I see it happen all the time and its EXTREMELY annoying since most people dont actually read the original source.

[edgeofsins]

He needs a n4g section

[RememberThe357]

No, offence to N4G. They used to regulate that stuff but I've noticed they've been allowing a lot more fluff in now days. The submission system still isn't quite right. Thats actually why I don't contribute anymore; far too much manipulation by sites that want hits.

[RedHawkX]

because mark cerny is just to awesome and his intelect cant be contained in just one article lol. you need to read up on these articles so you can learn something boy. positive emotions not these negative ones that you are displaying right now son.

[Pancit_Canton]

Mark is spreading the second coming of the king of console. The book of revelation of gaming shall be fulfill this holiday 2013

[Pisque]

Lol the previews say that the game is awful.

[Abriael]

Eh, previews say a lot of things. I'd say it's a tad early to judge a game that's still five months away no?

[lucaskeller1]

I watched the whole youtube presentation posted by the official playstation channel, it was technical at some points but I was engaged for the whole 47 mins and I learned a lot even about previous playstation consoles. I was amazed at how involved Cerny was with playstation since day 1 in 1994 but only found out about him at the feb reveal for ps4

[Abriael]

Yep, Cerny is probably the best narrator I heard in a lot of time. I don't think I know anyone else that can talk about GDDR RAM, bus and bandwidth and make it feel like the most awesome bedtime story.

[Groo]

LMAO!! I watched his presentation too and it was very calming lol. It would be the perfect bedtime story. hats off to you

[FarCryLover182]

Cerny is very, very wise.

[Thomper]

And very, very creepy...in a Star Trek enemy kind of way....

[Rainstorm81]

He'd be a perfect Edward Nigma...Riddler

[karl]

not in technical terms... just looking at that picture from the article comparing architectures..

the one on the left allows developers to acces the 176GB per seconds from the start

while the one on the right would only allow them to use 88GB per second at first

they would only unleash the other 1000GB when the small EDram chip or whatever is mastered right?

and that would take a few years.. im i right?

[MoonWheel]

Yea that is basically it. The 1000Gig is nice, but Sony wants developers to actually like their console lol. 176 gig of memory bandwidth is still plenty though.

[Abriael]

Not exactly actually. The 88 Gb per second of the second architecture still remain even after years, but for select uses they can push the 1000 GB, while the 176 GB of the PS4's architecture are for all accesses.

It's not as simple as early vs late. The 1000 GB wouldn't be available for everything.

[r1sh12]

yeah..although many of the devs will know how to make good use of edram.
Maybe not the best, but they might get there.

Sonys approach is pretty interesting, I wonder if they can re-direct the GPU memory into RAM or vice versa

[theWB27]

So basically what is being said developers preferred the unified architecture like a certain system did 8 years ago? Cerny built a much more advanced version of it. Very powerful version. Check..now this unified approach is being praised like it's new.

Wow...go get your praise Cerny : )

[MasterCornholio]

Well if you study the specifications of 7th generation systems none of them had a unified memory architecture. The PS3 memory was split up with DDR3 and XDR memory while the Wii and the Xbox 360 had their memory split up between DDR3 memory and eSram.

With the 8th generation of consoles the only system with a unified memory architecture is the PS4 with one pool of GDDR5 ram while the Xbox One uses DDR3 ram with eSram and the Wii U uses DDR3 with edram and esram.

Motorola RAZR i

[theWB27]

The architecture that sits beneath the processor is rather radical, and it's something that, quite honestly, we're still trying to get our heads around. Rather than using separate graphics and system memory, it appears that the Xbox 360 uses a unified memory architecture that splits the memory as it needs. The actual memory itself is GDDR3, the same stuff you'll find on the latest graphics boards from ATI. There's no physics processing unit, which is something that was rumoured a while back. Instead, Microsoft are banking on the triple-core to handle those kinds of calculations. We are rather unlikely to see this kind of shared memory architecture in PCs any time soon, because it would require a substantial redesign of the entire platform, which isn't something that either AMD or Intel are keen to do right now.

Here's the link
http://www.bit-tech.net/col...

[wishingW3L]

This is ridiculous, theWB27 has 16 disagrees for stating a fact while MasterCornholio has 10 agrees for being wrong and writing nonsense. N4G users should be ashamed of themselves, that's some hardcore fanboyism and denial right there. -__-

The PS3 had 256MB of GDDR3 for GPU and 256MB of XDR for CPU. The X360 had a unified pool of 512MB of GDDR3 with some edRam to boost the overall bandwidth but it didn't work that well so most devs used the edRam for free x4 MSAA. The funny thing is that they are committing the same mistake again with the XB1's unified pool of DDR3 with some esRam to boost bandwidth.

BTW GDDR3 and DDR3 are not the same thing!

[Bigpappy]

'Master' you got pieces of your info confused. 360 had 100% unified RAM. 'theWB' is correct. eSRAM in the 360 was only there to cache and increase bandwidth. It is not split memory like PC3.

[TheHardware]

Why would that matter? GDRR5 wasn't done, 8 gigs weren't done, and didn't the ps2 have unified ram? havent computers used unified ram forever? ooooohhh I wonder where Microsoft got the idea from...ooooohhhh

how silly can we be on these forums.

[theWB27]

No it didn't. Don't know about CPU's. But CPU's are custom machines so are they really comparable to closed systems? No. Yea...the systems are becoming more like PC's in structure I hear.

I won't argue about wondering where Microsoft got the idea from since..lo behold they've always worked with computer architecture. So is it strange they've always mimicked that structure? Until now where they've gone a lot more custom with the X1. Didn't think that had to be pointed out but owell.

[DivineAssault]

Mark Cerny took every single step possible to make PS4 the best nx gen console possible & achieved just that.. Best design, best controller, best specs, & best price..Too bad M$ doesnt have passionate people working for them that go the extra mile like he did.. The only thing M$ people are passionate about is getting money out of its customers in every way..

Unlike PS controllers that have internal lithium batteries, xbox controllers need AA batteries (wasting money every time they run out) unless you buy a play n charge kit from em (giving them more money).. Storage space on PS4 can be upgraded but the xbox requires you to buy a HDD from them (giving them more money) because its proprietary.. PS4 offers online features other than multiplayer for free but xbox requires xblg (giving them more money) just to use netflix & other various apps online.. Indie devs can self publish on PS4 but not on xbox (giving them more money).. The list goes on & on..

The point is that M$ made a decent machine but theyre a greedy company & tries to milk everyone.. Especially with xbox one.. Forcing people to pay an extra $100 for a bundled in camera (giving them more money) cuz it wont work without kinect plugged in.. Well, they wont be getting a damn cent from me nx gen.. Im sticking with Sony & Nintendo only until i see some major changes take place..

[theWB27]

So your point is...that's why Microsoft isn't a company selling off assets and didn't have to give the boss a bonus for finally not operating in the red.

[stuna1]

So since they are the cream of the crop (Microsoft), why are they restructuring? Because obviously someone seems to think that they are not handling things as they should!

Just because someone enjoys licking Microsoft boots, doesn't mean everyone should enjoy licking their boots.

[theWB27]

@stuna1
They're restructuring because Steve Ballmer is shifting the companies focus...not because the company is operating at the disastrous losses that Sony was for what, 5 or so years. They aren't selling off buildings and splitting divisions so it "appears" things are that much better.

http://www.techspot.com/new...

So since they are a better business than(Sony)why aren't they selling off the business? Because obviously someone was blatantly not handling things the same way they were at Sony!!

Just because someone enjoys not knowing what they're talking about, doesn't mean everyone should enjoy not knowing what they're talking about.

I don't mind you trying to be clever. Just be better at it next time. I won't comment on the licking boots cause quite honestly you don't know me. PS3/360 owner...planning the same this upcoming gen. Enjoy your day stuna1.

[stuna1]

The licking of the boots comment wasn't directed at you in general! But in response to not knowing what I'm talking about, I know fully well what what I'm talking about, since I do have Microsoft stock! I won't go into details, but in this time frame I'll just say that a lot of the big investors are not as happy as some may perceive! Especially after the backlash they are receiving about their gaming division as well as the NSA leak.

[GrandTheftZamboni]

@theWB27
Just because MS is good at one thing such as selling their OS doesn't mean they are successful at everything else they do. If MS didn't have Windows and Office they wouldn't exist. There would be no Xbox.

[Picture_Dancer]

Bubble up, because it is "well said"

[Lwhit6]

Soooo from my understanding there isnt much of a difference between GDDR5 and GDDR3? Except that GDDR5 is easier for developers to produce games for?

[Abriael]

I'm not exactly sure where you read that. There's a rather big difference between GDRR5 and GDRR3, but this doesn't even talk about GDRR3.

[Tundra]

GDDR5 makes it easier to run a game at higher resolution with added effects such as super sampling, Anti-Aliasing, AF, higher res textures, etc without performance hits.

GDDR5 pretty much doubles the memory bandwidth of GDDR3 under the same conditions with RAM clock speed and the bit-bus.