Howdy, Stranger!

It looks like you're new here. If you want to get involved, click one of these buttons!

Fuzzy Avatars Solved! Please re-upload your avatar if it was fuzzy!

AMD's Kaveri with DDR5 ram?

TheLizardbonesTheLizardbones Arkham, VAPosts: 10,910Member

I have heard that AMD's Kaveri will not support DDR5 ram, which is going to bottleneck performance compared to a discrete AMD cpu and gpu. Can anyone confirm that the new A10 APUs will be limited to DDR3 ram? Is there any particular reason why? For instance, if the new A10s supported DDR5 ram, would it push performance too high and tank sales of AMDs CPUs?

Just wondering. I've been looking at the new A10s, thinking it would be really cool to have a system that doesn't use a ton of power, and was pretty quiet, and less expensive than a full upgrade.

I can not remember winning or losing a single debate on the internet.

Comments

  • QuizzicalQuizzical Posts: 14,784Member Uncommon

    There is no such thing as DDR5 memory.  You may mean GDDR5.

    One major downside to GDDR5 is that you're limited to four memory chips per memory channel, whereas DDR3 can easily have 16 or 32 or whatever.  Today, that means at most 2 GB of memory per channel.  That means that a 128-bit memory bus caps you at 4 GB.  For a lower end video card, that's an enormous amount, making it an inconsequential restriction.  For a desktop processor, 4 GB total system memory plus video memory added together isn't much.

    Another downside to GDDR5 is that it is power hungry, which would make it unsuitable for use in low-power laptops.  Kaveri is primarily a laptop chip, and a laptop chip that isn't suitable for laptops isn't likely to end well.  Not that that ever stopped Intel from pushing Pentium 4 for laptops.

    There are trade-offs between power and performance in memory, as with some other components.  GDDR-anything goes for high performance and accepts the drawback of high power consumption.  LPDDR-anything goes primarily for low power consumption, and accepts that this means reduced performance.  Normal DDR-anything is somewhere in between.  Discrete video cards usually go for GDDR5, while cell phones or tablets want LPDDR-whatever, and desktops and laptops take ordinary DDR-something.

  • TheLizardbonesTheLizardbones Arkham, VAPosts: 10,910Member


    Originally posted by Quizzical
    There is no such thing as DDR5 memory.  You may mean GDDR5.One major downside to GDDR5 is that you're limited to four memory chips per memory channel, whereas DDR3 can easily have 16 or 32 or whatever.  Today, that means at most 2 GB of memory per channel.  That means that a 128-bit memory bus caps you at 4 GB.  For a lower end video card, that's an enormous amount, making it an inconsequential restriction.  For a desktop processor, 4 GB total system memory plus video memory added together isn't much.Another downside to GDDR5 is that it is power hungry, which would make it unsuitable for use in low-power laptops.  Kaveri is primarily a laptop chip, and a laptop chip that isn't suitable for laptops isn't likely to end well.  Not that that ever stopped Intel from pushing Pentium 4 for laptops.There are trade-offs between power and performance in memory, as with some other components.  GDDR-anything goes for high performance and accepts the drawback of high power consumption.  LPDDR-anything goes primarily for low power consumption, and accepts that this means reduced performance.  Normal DDR-anything is somewhere in between.  Discrete video cards usually go for GDDR5, while cell phones or tablets want LPDDR-whatever, and desktops and laptops take ordinary DDR-something.

    Since DDR5 doesn't exist, then yes, I meant GDDR5. :-)

    There are apparently going to be some BGA parts with the A10s soldered on the board, with 4GB of the GDDR5 ram. If 2GB GDDR5 chips start to exist, then there may be A10s with 8GB of the GDDR5 ram showing up with the chips soldered on the board.

    I keep reading about AMD's Axx APUs because the idea seems very attractive. A consolidated, low heat and thus quiet system with the trade off being that it's not going to deliver top end graphics. Which is fine, because right now I'm running an Intel Q6600 with an AMD HD5770, so top end graphics isn't a super high priority. The A10-7800k seems like it might be a good value for the money, and adding an R7-2xx card later to improve graphics performance is a possibility too. It seems like I could spend almost the same amount of money and get an AMD cpu with a much better GPU and get better performance though. Which is a different question altogether.

    I can not remember winning or losing a single debate on the internet.

  • QuizzicalQuizzical Posts: 14,784Member Uncommon

    The first 2 Gb (= 256 MB) GDDR5 memory chips only came to market earlier this year.  The prospect of such chips arriving on time and in sufficient volume are what allowed the PS4 to switch from 4 GB to 8 GB and rob the Xbox One if its lone hardware advantage.  But I wouldn't count on 4 Gb chips showing up anytime soon.

    4 GB really just isn't enough for a gaming rig anymore.  Remember that that's not just system memory alone; it's system memory plus video memory.  Reserve 1 GB for video memory and you have 3 GB for system memory, which could easily be problematic.

    Furthermore, I wouldn't be terribly keen on having everything soldered to the motherboard.  Do you really want the failure of a memory chip to mean that your motherboard, CPU, and GPU are all dead?  And in a laptop, GDDR5 is too power hungry for use as main system memory, as that will drain your battery too fast.

    DDR4 would have been nice, but it's not ready yet.  I fully expect AMD's next high-end APU (rumored code name Carrizo) to have DDR4 memory.  Unfortunately, that will mean yet another new socket.

  • TheLizardbonesTheLizardbones Arkham, VAPosts: 10,910Member


    Originally posted by Quizzical
    The first 2 Gb (= 256 MB) GDDR5 memory chips only came to market earlier this year.  The prospect of such chips arriving on time and in sufficient volume are what allowed the PS4 to switch from 4 GB to 8 GB and rob the Xbox One if its lone hardware advantage.  But I wouldn't count on 4 Gb chips showing up anytime soon.4 GB really just isn't enough for a gaming rig anymore.  Remember that that's not just system memory alone; it's system memory plus video memory.  Reserve 1 GB for video memory and you have 3 GB for system memory, which could easily be problematic.Furthermore, I wouldn't be terribly keen on having everything soldered to the motherboard.  Do you really want the failure of a memory chip to mean that your motherboard, CPU, and GPU are all dead?  And in a laptop, GDDR5 is too power hungry for use as main system memory, as that will drain your battery too fast.DDR4 would have been nice, but it's not ready yet.  I fully expect AMD's next high-end APU (rumored code name Carrizo) to have DDR4 memory.  Unfortunately, that will mean yet another new socket.

    It would really depend on the price. If the BGA part was cheap enough, then yes, I'd be fine with replacing it if a memory chip went bad. I doubt it would be cheap enough though. I can't imagine they're going to make a ton of microatx or miniatx boards like that.

    So the real question is whether or not a Kaveri chip would give acceptable performance relative to the same amount of money spent on a discrete cpu/gpu combo, even if the combo was louder.

    It's like AMD is just teasing everyone. Here's an awesome, easy to setup thing that is sooo much more efficient, but wait! Here's the boogie man caveat! Ha ha sucker!

    I can not remember winning or losing a single debate on the internet.

  • RidelynnRidelynn Fresno, CAPosts: 4,179Member Uncommon


    Originally posted by Quizzical
    Furthermore, I wouldn't be terribly keen on having everything soldered to the motherboard.  Do you really want the failure of a memory chip to mean that your motherboard, CPU, and GPU are all dead?

    I'm kinda in the same boat as lizardbones on this one:

    Sure, I don't want stuff to break, and if it does break I want it to be easy to fix. But more important the being easy to fix, I don't want it to break in the first place. And if everything is attached onto one board, that all of a sudden becomes very easy to fix - it's just a matter of economics at that point.

    I'm not upset that the sound card on my motherboard isn't socketed and easily replaceable. I'm not upset that each individual capacitor in my power supply isn't socketed and easily replaceable. Blowing up a $0.35 capacitor from Radio Shack renders my entire $100 PSU unusable - but no one complains about that.

    Sockets do add a lot of cost of the base component, and if we're being honest about RMA's in the first place, I'd say half of all parts that get RMA'ed are done so because the user installed it into the socket wrong (bent a pin on a CPU, hammered a DIMM in backwards, something - I've seen it all), and that just drives up costs for everyone on the back end (the company isn't just taking that as a loss). Sockets also take up a lot of space compared to being able to just solder components on a board, and are much less reliable than a straight soldered connection.

    As long as the soldered all-in-one board has a reasonable warranty I'd have no problem with it at all. I don't even think it needs to go out to something absurdly long - just long enough so that when something does break (because it is inevitable, after all), the decision to repair/replace it or upgrade it in the first place ends up being a real consideration. 2-3 years feels about right, that gets you 1-2 generations ahead in hardware and would be about the right time frame to start considering an upgrade anyway, and if it breaks before then the warranty covers repairs.

  • QuizzicalQuizzical Posts: 14,784Member Uncommon

    If the integrated sound on your motherboard dies, you don't have to replace the motherboard.  You can get a discrete sound card and use that instead.

    More components soldered on also means it's harder to get a sensible hardware configuration.  It's pretty easy to get a good hardware configuration for just about any budget in a desktop.  For a laptop, it's much, much harder.  Still, if they're using GDDR5 soldered on, that would basically guarantee that everything has 4 GB.

    There is also a JEDEC standard for GDDR5M on separate modules.  I'm not sure if that makes it possible to have more memory or not.  If it does and Kaveri goes that route, then it could be a nice setup if it's ready for widespread use.  Of course, that would mean that you'd need yet another new socket, as the current FM2+ motherboards built for Kaveri wouldn't be able to take GDDR5M.

  • TheLizardbonesTheLizardbones Arkham, VAPosts: 10,910Member

    It's too bad they can't have a board with GDDR5 ram soldered on, but with slots for DDR3 ram. The GDDR5 would be for the video part of chip, and the memory slots would be for the rest. Though I guess that breaks the whole shared memory thing and then they're shuttling things back and forth from the GDDR5 to the DDR3.

    Even with the DDR3 "roadblock" though, the current A10s still turn pretty good numbers. Better than a comparable Intel setup anyway. :-)

    I can not remember winning or losing a single debate on the internet.

  • QuizzicalQuizzical Posts: 14,784Member Uncommon
    Originally posted by lizardbones

    It's too bad they can't have a board with GDDR5 ram soldered on, but with slots for DDR3 ram. The GDDR5 would be for the video part of chip, and the memory slots would be for the rest. Though I guess that breaks the whole shared memory thing and then they're shuttling things back and forth from the GDDR5 to the DDR3.

    They can, and in fact, I think it makes some sense to do that.  Solder a single, cheap 64 MB GDDR5 chip onto the motherboard and have a 32-bit connection to it.  That one chip will get you far more memory bandwidth than a normal DDR3 memory channel, even for fairly high clocked DDR3.  Use the GDDR5 chip for the depth buffer and framebuffer, while reading textures and other such stuff from shared DDR3 system memory.  Give BIOS and video driver options to disable the extra GDDR5 chip to handle corner cases or in case it dies.

    AMD has done something kind of like this before with the 790GX chipset, though the extra video memory was DDR2 or DDR3.

  • TheLizardbonesTheLizardbones Arkham, VAPosts: 10,910Member

    Hmmm, maybe something like that will pop up before April '14*. It would be cool, very "high tech", and something that would appeal on performance and power consumption. Until then, I guess I'll be watching benchmarks and comparing prices to see if DDR3 really is a noticeable bottleneck or not.

    **

    * I don't think so, everything I've read points to either DDR3 slots or GDDR5 with everything soldered on the board. It would be cool though.

    I can not remember winning or losing a single debate on the internet.

Sign In or Register to comment.