News Samsung launches 8Gb GDDR5 chips, hints at PS4 redesign

Discussion in 'Article Discussion' started by Gareth Halfacree, 15 Jan 2015.

  1. Gareth Halfacree

    Gareth Halfacree WIIGII! Staff Administrator Super Moderator Moderator

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  2. andrew8200m

    andrew8200m Well-Known Member

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    The PS4 is small enough as it is. Any smaller and itll feel cheap like the last lot did. they would be mad to redesign now given they already have the market lead by a considerable margin.
     
  3. edzieba

    edzieba Virtual Realist

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    The PS4 currently uses 16 4gb modules. If they switched to 8gb modules, each module would need not only double the bandwidth, but would need to do it in a way that does not reduce the parallelism that games may be coded to take advantage of (i.e. you couldn't just run the interconnects at twice the data rate with the same bus width).
     
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  4. andrew8200m

    andrew8200m Well-Known Member

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    Superb reply!
     
  5. Vallachia

    Vallachia Member

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    Exactly! So either these new Sammy chips have a double-wide interface or it's just posturing and spin from Sammy.
     
  6. Chicken76

    Chicken76 Member

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    Did you mean built?
     
  7. Chicken76

    Chicken76 Member

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    That's only a concern if the chip has 16 memory controllers (or channels). If it has 8 or fewer, then there won't be any change in parallelism.
     
  8. Gareth Halfacree

    Gareth Halfacree WIIGII! Staff Administrator Super Moderator Moderator

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    Yes. Yes, I did. Fixed, ta!
     
  9. Corky42

    Corky42 What did walle eat for breakfast?

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    Am i being my normal stupid self this morning, or should this...
    Read as...

    A 1GB DIMM may, for example, be made up of eight individual 512MB DRAM chips.
     
  10. Gareth Halfacree

    Gareth Halfacree WIIGII! Staff Administrator Super Moderator Moderator

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    My version is correct. A shock, I know. Note the capitalisation of the B: a lower-case b indicates bits; an upper-case B indicates bytes. There are eight bits in a byte¹, so one gigabyte equals eight gigabits. Eight 1Gb (one gigabit) memory chips connected together on a DIMM would give 1GB (one gigabyte) of storage capacity.

    Eight 512MB (five hundred and twelve megabyte, or half-gigabyte) DRAM chips, by contrast, would give 4GB (four gigabyte) of storage capacity.

    ¹ For the purposes of our discussion there are, anyway. Yes, some systems have used oddly-sized bytes, but PC DRAM doesn't so I'm choosing to ignore that little fact.
     
  11. Cei

    Cei pew pew pew

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    I doubt it. Samsung are suggesting that Sony can halve the number of RAM chips in the PS4, which saves how much space exactly?

    Oh right, not much. The PS4's size isn't especially dictated by the logic board either, but by the physically big items in the case, namely the PSU, BD drive, HD bay and cooling fan assembly. These items aren't going to be getting smaller any time soon, and in their nature dictate a certain size of case. Shrinking the PCB may save a few centimetres at best.
     
  12. Gareth Halfacree

    Gareth Halfacree WIIGII! Staff Administrator Super Moderator Moderator

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    Quite a lot, actually - at least, when you include supporting power circuitry and board traces.
     
  13. Cei

    Cei pew pew pew

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    [​IMG]

    RAM is the orange outline. That's a few centimetres at absolute best. Compared to the PSU it's nothing!

    [​IMG]
     
  14. Gareth Halfacree

    Gareth Halfacree WIIGII! Staff Administrator Super Moderator Moderator

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    Now read my *entire* sentence. Chip footprint is not the biggest cost, here. (Also, count the chips: you're missing half of 'em in that picture.)
     
  15. Cei

    Cei pew pew pew

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    I did read! Yes, there'll be some additional tracings and power circuitry that can be removed, but equally that board has acres of empty space on it already. Looking at the board tracings, the interconnects from the APU to the cluster of chips on the bottom left will remain. All you'll remove is the very short runs from 1/2 the RAM to the APU and a minority fraction of the power circuitry at the top.

    Yes, half the chips are missing, they're on the other side in exactly the same place and configuration. So you can remove half from the image above, as you'll also be removing their matched partner on the flip side of the board.

    I stand by the fact that you might be able to shave a few cm off the board size. Obviously cm2, since it's an area.

    EDIT
    [​IMG]
    C'mon, that isn't a lot of space on a board.

    To make a smaller PS4 you need to die shrink the APU, which allows a smaller cooling unit and a smaller lower wattage PSU. Add in the tiny saving made by moving to higher density RAM and you've probably got enough to make a noticeably smaller case.

    Look at the Ps3 as an example. The Super Slim came about due to a switch from a slot loading drive to a top loader that saved on space. It used the die-shrunk Cell and RSX from the original re-design of the PS3, which was what enabled Sony to get away from the rather large fat launch models due to a redesign of the cooling system thanks to lower power draw and temperatures. Sony also cheated a bit by removing USB ports and things like TOSLINK. The PS4 doesn't have the luxury of additional ports than can be sacrificed - it only has two USB3 ports!
     
    Last edited: 21 Jan 2015
  16. Gareth Halfacree

    Gareth Halfacree WIIGII! Staff Administrator Super Moderator Moderator

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    (Apologies for aggressive snipping, here, as I'm on my phone.)

    If I were redesigning the PCB, I'd leave the top chips alone and move some other components to where the bottom chips used to be to save maximum space.

    Also, you're thinking two-dimensionally. Look up a picture of a BGA-packaged GDDR5 chip and count the number of solder balls on the underside. Every single one of those needs a PCB trace. The ones you see on the top of the board are part of the story: there are twenty-some layers to that PCB, and traces in all of them. Traces can't cross over each other on the same layer: the more traces you have, the more layers you need and the more complex the PCB. After a while, you hit an upper limit of layers and you need to start tracing circuitous routes to avoid existing traces, often jumping between layers using vias. What you see as empty areas of PCB are likely *filled* with traces you can't see - otherwise their be wasted space, and nobody likes wasted space - least of all the bean-counters.

    Am I suggesting that simply halving the RAM chips will let Sony build a pocket-sized PS4? No. Am I suggesting that it could be combined with other advances made in the last two years (a more efficient PSU, perhaps, or new stepping of APU which draws less power) to build a PS4 smaller than the existing model? Yes
    They've done exactly that in previous generations, so why are you suggesting it's impossible now? What makes the PS4 so different to the PS3, or PS2, or PS - all of which got slim variants, despite the original designs being exactly as jam-packed and optimal as e PS4?
     
  17. Cei

    Cei pew pew pew

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    I think we're kind of on the same page. I'm saying that to shrink the PS4 it needs to be a combination of an APU die shrink, increased RAM density and a 'better' PSU (be that more efficient or lower wattage due to reduced power draw). Yes, that's exactly what Sony did previously, which was in my post :)

    Samsung, on the other hand, seem to be saying it's the RAM alone that is stopping Sony making a smaller PS4. Which is bunk. A PS4 shrink is 2-3 years away, not on the horizon.
     
  18. Gareth Halfacree

    Gareth Halfacree WIIGII! Staff Administrator Super Moderator Moderator

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    Ah, but that part of the post wasn't present when I started composing my reply - sneaky! ;) (As an aside: blimey, it's good to be back on the desktop. Editing replies on the phone is horrid.)
    Well, no: as the article says, all Samsung is saying is that its new RAM could reduce the number of chips used in the PS4 (well, the games console that uses GDDR5 - which is the PS4) if used as a replacement for the (Samsung, incidentally) 512Mb chips currently in use with no cost to performance (to address the "but parallelism" complaint from above that I missed originally: given Intel's flagship Haswell-E processors' memory controller is quad-channel, what do you think the chances are that AMD's poor ickle Jaguar-based APU has a sixteen-channel memory controller on board to address all 16 512Mb chips at once? Choose from: no chance, zero chance, or not a chance in heck.) All Samsung cares about is a redesign of the PCB to accommodate its new chips; it couldn't give two hoots if the revised PS4 that results is smaller, the same size, or even bigger.

    EDIT:
    Almost completely off topic, but related to memory density and PCB design: the PCB for Uncle Clive's classic ZX81 microcomputer had room for two different density memory chips. Depending on what was available on the market at the time, it would arrive fitted with two 4Kb (512B) or one 8Kb (1KB) DRAM chips. You can see it on this picture of mine: my kit came with two 4Kb chips, but you can see a larger silk-screen (and the matching holes) for a bigger component marked IC4. That would have been the 8Kb chip, if it had been used. This way, Uncle Clive could use whatever RAM was cheapest on the market at the time without having to redesign the PCB. Externally, of course, the ZX81 would look identical - you'd never know whether it had one or two RAM chips inside, apart from perhaps measuring the slightly lower power draw of the one-chip variant.
     
    Last edited: 21 Jan 2015

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