AMD 2015 Roadmap: Toronto, Cambridge , there DDR4

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Chiropteran

Diamond Member
Nov 14, 2003
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DDR2 and DDR3 did have identical pins. The DIMM sockets was not compatible because one was 1.35V/1.5V the other 1.8V. So they moved the key notch to prevent user errors.

Exactly, moving the notch makes them non-identical. Yet this difference was easily handled by motherboard manufacturers.

Why can't they do the same thing with DDR3 and DDR4? For example, the extra pins used in DDR4, they could just *not use them* in the DDR3 sockets. It doesn't seem like rocket science to me. Remember, it was possible to support both SDR DIMMs and DDR DIMMs on the same board, with different pin-counts.
 

ShintaiDK

Lifer
Apr 22, 2012
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Exactly, moving the notch makes them non-identical. Yet this difference was easily handled by motherboard manufacturers.

Why can't they do the same thing with DDR3 and DDR4? For example, the extra pins used in DDR4, they could just *not use them* in the DDR3 sockets. It doesn't seem like rocket science to me. Remember, it was possible to support both SDR DIMMs and DDR DIMMs on the same board, with different pin-counts.

Just not use the pins? Really? Why do you think they are there in the first place? Because they are not needed? :p

And the SDR vs DDR have already been explained to you, twice.
 

Chiropteran

Diamond Member
Nov 14, 2003
9,811
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Just not use the pins? Really? Why do you think they are there in the first place? because they are not needed?

They aren't there for DDR3. They are there for DDR4. For DDR3, you would *not* use the extra pins, because they are not needed- they are not part of DDR3. For DDR4 support, you would use them.

And the SDR vs DDR have already been explained to you, twice.

Uh, your explanation was that the chipset supported both. With modern APU, that part of the chipset is the integrated memory controller, which is part of the processor, which could *also* support either or both. Therefore your explanation is not useful, and doesn't actually explain anything.
 

ph2000

Member
May 23, 2012
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i thought it was stated in the OP
Another plus is that AMD would be shipping Carrizo with both DDR3 and DDR4 memory support so its highly possible that Carrizo would feature support on FM2+ boards with DDR3 memory and also a new socket that would allow DDR4 memory support
 

ShintaiDK

Lifer
Apr 22, 2012
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They aren't there for DDR3. They are there for DDR4. For DDR3, you would *not* use the extra pins, because they are not needed- they are not part of DDR3. For DDR4 support, you would use them. .

Yes, thats why FM2/FM2+ supports DDR3 and not DDR4. Because the extra pins are not there. Plus the pins are not compatible.

Uh, your explanation was that the chipset supported both. With modern APU, that part of the chipset is the integrated memory controller, which is part of the processor, which could *also* support either or both. Therefore your explanation is not useful, and doesn't actually explain anything.

Unlike the chipset, you need sockets for the CPUs, with fixed pincounts. if you wanted support for both DDR3+DDR4, you would need a BGA layout with additional pins, or a new socket.
 

ShintaiDK

Lifer
Apr 22, 2012
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and the slide says it OPTERON

then again is there any reason why it cannot materialize in new FMx socket?

It would have to be FM3 and not FM2/FM2+.

But again, there is no FM3.

AMD own roadmap for the desktop. No DDR4:
AMD-Carrizo-APU-Desktop-Roadmap.png
 

Chiropteran

Diamond Member
Nov 14, 2003
9,811
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Yes, thats why FM2/FM2+ supports DDR3 and not DDR4. Because the extra pins are not there. Plus the pins are not compatible.

Yes, this makes sense. It was your original "you can't support both DDR3 and DDR4 because they aren't pin compatible" statement I had issue with.
 

ShintaiDK

Lifer
Apr 22, 2012
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Yes, this makes sense. It was your original "you can't support both DDR3 and DDR4 because they aren't pin compatible" statement I had issue with.

They are not pin compatible. You really need to read up on the subject. Its hard to take you serious when you just claim the extra pins used for DDR4 is not needed.
 

Erenhardt

Diamond Member
Dec 1, 2012
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They are not pin compatible. You really need to read up on the subject. Its hard to take you serious when you just claim the extra pins used for DDR4 is not needed.

There was a way to put AM3 phenom into AM2 motherboard. Clearly not pin compatible, but if one was brave enough to cut out a pin or two from the CPU, he could enjoy an upgrade.

Did you know that human can live with two fingers less in each hand without any problems? ;)
 

Shivansps

Diamond Member
Sep 11, 2013
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man wth, 2 pages to understand that is NOT the same having the memory controller on cpu than on NB on motherboard, and as results is not the same thing connect memory to CPU socket than connecting them to NB chip?

come on... you now what? if Intel mades a DDR4 chipset for 775, then all 775 cpus should be able to run DDR4, same aplies to Athlon XP...

Such thing is just impossible on a CPU that already have a integrated memory controller, thats why AMD had to work hard on the 754, 939 and finally AM2 era, AM2 to AM3 was easy as both rams had the same pins, as result the MB could support both as long the CPU memory controller suported it, thats why the jump to AM3, just to separate cpus that could not support DDR3.

Even if DDR4 where pin compatible to DDR3, its likely that AMD whould do the same again and launch the FM3.

But for DDR4 they just new a completely new socket with not backward compatibility, the pin diff is way too much.
 

ShintaiDK

Lifer
Apr 22, 2012
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sefsefsefsef

Senior member
Jun 21, 2007
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DDRx and LPDDRx have totally different standards, and generally have nothing to do with each other.

There's nothing keeping AMD from putting both a DDR3 and DDR4 memory controller in Carizzo. At the dice level (pre-packaging) they could just reconfigure some of the IO pins to create either DDR3 or DDR4 interfaces. This is not unbelievable or innovative at all. For example, nVidia and AMD both already do this all the time with their GPUs that support both DDR3 and GDDR5 memory.

It is true that DDR3 and DDR4 would require different motherboards and sockets, though, but there's nothing to keep AMD from producing DDR3 compatible Carizzos *and* DDR4 compatible Carizzos (2 different sockets, 2 separate ranges of Carizzo SKUs). I don't see why this would be hard to believe.
 

ShintaiDK

Lifer
Apr 22, 2012
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It is true that DDR3 and DDR4 would require different motherboards and sockets, though, but there's nothing to keep AMD from producing DDR3 compatible Carizzos *and* DDR4 compatible Carizzos (2 different sockets, 2 separate ranges of Carizzo SKUs). I don't see why this would be hard to believe.

Nobody have disagreed in that. Hence pointing out that DDR4 will most likely be BGA. Its just not gonna happen on the FM2+ socket.
 

jpiniero

Lifer
Oct 1, 2010
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DDR4 is going to be too expensive for AMD's desktop and laptop lines in 2015; so if it does happen it would be only for the server APUs.
 

Homeles

Platinum Member
Dec 9, 2011
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Support would be enabled at a chip level, since the memory controller is integrated. You'll undoubtedly see some vendors opt to use DDR4.
 

Ajay

Lifer
Jan 8, 2001
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Nobody have disagreed in that. Hence pointing out that DDR4 will most likely be BGA. Its just not gonna happen on the FM2+ socket.

Really makes me wonder what AMD is going to do with Carrizo for iGPU. If Carrizo is to make any progress in GFX performance, AMD needs some sort of higher bandwidth solution. They just haven't given any clue as to what that will be - unless I've missed something.
 

Fjodor2001

Diamond Member
Feb 6, 2010
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Maybe AMD will go after the BGA and small All-In-One Desktop PC market with Carrizo (and pair it with DDR4)? Isn't that what Intel intends to do with Broadwell too, providing BGA chips for desktops before the socketed Broadwell-K? Earlier there were even rumors of Intel skipping a socketed version of Broadwell completely, but that they finally changed their mind and will release one (Broadwell-K) after all.

If you can't sell Desktop PCs based on inreased performance alone anymore since most users already have one that is "good enough", then maybe you can sell them on being smaller and more elegant. People don't like big bulky boxes on their desk if it can be avoided. Similar idea as with Ultrabooks, although there you also have the benefit of them being easier to carry around.
 

hawtdawg

Golden Member
Jun 4, 2005
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While I highly doubt its going to be anywhere close to 30%, if it is infact that much, then the IPC gains and APU performance could put it on par with intel yet again.

not unless TSMC magically skips a node.