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AM2 motherboard owners rejoice, AM2 has a long future

AMD has released details of its next-generation desktop CPU interface, Socket AM3, to its OEM partners.  In a mildly surprising move, AMD has revealed that AM2 will accept AM2 or AM3 (also dubbed AM2+) CPU packages.  Additionally, recent roadmaps have confirmed that AM3, AMD's upcoming desktop CPU socket, will not be backwards compatible with AM2-package CPUs.  Roadmaps and memos have also confirmed that this AM3 package will be for AMD's "K8L" architecture, and not for the upcoming 65nm AM2 Brisbane CPUs scheduled for launch this December.

The most recent AMD roadmap is also very clear to state AM3 "supports either DDR2 SDRAM or DDR3 SDRAM, but not on the same motherboard."  This is great news for upgraders, as there is a very clear upgrade path: CPU, motherboard, and then memory.  This also infers that AM3 CPUs will have both DDR2 and DDR3 support on the integrated memory controller.  DDR3, like DDR2, has 240-pin, but the two formats are not pin-compatible.

As we also mentioned earlier, Greyhound will be the first desktop processor to support HyperTransport 3.0. Part of the specification for HT-3 is backwards compatibility with older revisions of HyperTransport, and the forward compatibility of the AM2 socket confirms that.  However, it’s important to mention that even though AM3 CPUs will work in the AM2 socket, HT-3 allows for 5.2 Giga-transfers per second, while current AM2 motherboards top out at 2.0 Giga-transfers per second.  Even though the additional headroom is likely not completely necessary, quad-core CPUs will certainly benefit from the additional bandwidth to additional CPUs or co-processors.

There is no word yet on the number of pins the new socket will require, but since AM2 sockets are forward compatible with AM3 CPUs, we can at least deduct that AM3 will have fewer than 940 pins.  Furthermore, since Socket AM2 is forwards compatible with AM3 CPUs, it is also safe to say that AM3 is not a land-grid array (LGA) socket.  AMD will switch its Opteron platform to an LGA-1207 socket on August 1, 2006.  AMD has not announced when Socket AM3 will be released, although since it would be the first HT-3 "ready" socket design, it seems likely that K8L and AM3 for the desktop will launch simultaneously.

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Picky picky
By Burning Bridges on 7/6/2006 5:23:51 AM , Rating: 2
quote:
AM3 "supports either DDR2 SDRAM or DDR3 SDRAM, but not on the same motherboard." This is great news for upgraders, as there is a very clear upgrade path: CPU, motherboard, and then memory.

If it doesn't support DDR3 on a DDR2 board, then the upgrade path would be CPU -> Motherboard & RAM not CPU -> Motherboard -> RAM

Or is it just me?




RE: Picky picky
By psychobriggsy on 7/6/2006 6:47:13 AM , Rating: 2
Indeed, apart from situations where the AM3 motherboard has DDR2 memory slots, where you'll never be able to upgrade to DDR3...

Of course the CPU cost is going to be the same as Motherboard + RAM, it just means you can split your upgrade into two separate purchases, that coincidentally advantages AMD (upgrade your CPU sooner than you would have otherwise).

I guess AMD should be applauded for trying to make the next generation processor socket backward compatible, even if the socket change is coming around quite quickly. I also guess that there will be a *lot* of AM3 + DDR2 motherboards initially, when DDR3 memory costs a lot and isn't showing an advantage.


RE: Picky picky
By Furen on 7/6/2006 7:10:09 AM , Rating: 2
There's no benefit at all to making an AM3 motherboard that uses DDR2 since AM2 will run AM3 chips AND current AM2 K8s. I think we'll see AM3 chips hit the market en-masse but AM3 motherboards in very limited quantities (if at all), so the ultra-high end will be able to jump on DDR3 ram while the more-budget-concious can stick to DDR2 (basically so Intel can't have the "DDR3 advantage" like it did with DDR2 for so long).


RE: Picky picky
By Master Kenobi (blog) on 7/6/2006 9:11:34 AM , Rating: 1
Intel is going down the FB (Fully Buffered) memory path, AMD doesnt seem to be following.


RE: Picky picky
By coldpower27 on 7/6/2006 11:22:26 AM , Rating: 2
Well not exactly, they are going FB-DIMM for servers which is based on DDR2 technology. AMD is going to give the user the option so they say and support both Registered DDR2 and FB-DIMM's.



RE: Picky picky
By saratoga on 7/6/2006 2:11:28 PM , Rating: 2
FB increases latency (even more over DDR2/3) but allows you to have more DIMMs. Its a great tech for servers since it allows people to have 6 or 8 DIMMs per chipset (or Opteron in AMD's case) without having too larger of a performance hit.

Its not clear that it will ever be on the desktop since most people don't seem to need more then 4 DIMMs on a consumer level board and probably wouldn't want to have higher latency and cost to get it even if they wanted 8 DIMMs.


RE: Picky picky
By jsrivo on 7/6/2006 9:22:39 AM , Rating: 2
I thought they meant that DDR2 memory may not be placed on the same motherboard also populated by DDR3 memory, and vice versa. So you could buy an AM3 motherboard which would still support DDR2, and then you could buy DDR3 memory afterwards to replace those DDR2 modules.

Am I reading this wrong?


RE: Picky picky
By Master Kenobi (blog) on 7/6/2006 10:12:01 AM , Rating: 2
Yes. the DDR2 and DDR3 DIMM's have different pin offsets so you cant fit them mistakenly into the same sockets. The processor will accept either DDR2 or DDR3, but its up to the motherboard's Dimm slots to determine which you can use.


RE: Picky picky
By jsrivo on 7/6/2006 10:23:19 AM , Rating: 2
Ah. Thanks for clearing that up.


RE: Picky picky
By breethon on 7/6/2006 6:52:27 PM , Rating: 2
But, why can't they develop a motherboard that supports both (just not at the same time) like for instance ECS makes a board that supported SDRAM and DDR (just not together) for the Socket A platform. It worked nicely by the way.


RE: Picky picky
By mino on 7/6/2006 8:17:28 PM , Rating: 2
They CAN. And AsRock/ECS will.


Any word on the release date for socket AM3 chips?
By Furen on 7/6/2006 1:28:02 AM , Rating: 5
The more important question, in my opinion, is when we'll start seeing AM3-packaged chips. K8L does sound interesting but this makes me wonder just WHEN we'll see it released, since I doubt AMD will introduce a new socket less than a year after introducing an old one.

Since AM2 can drive AM3 chips I suppose releasing AM3 packaged chips does not mean that we'll see the motherboards out at the same time. This could lead to an interesting socket/CPU phasing: socket AM2 can drive AM2 and AM3 chips, so socket AM3 could, for example, drive AM3 and AM4. This would make sockets compatible with two "generations" of chips but would require the memory controller(s) to drive two different memory standards (which is the only reason why AMD would have to change sockets). Also, releasing AM3 chips that can drive both DDR2 and 3 (and plugs into both AM2 and AM3) means that AMD can change memory standard as soon as it wants to, without worrying about making its past processor lines




By AnotherGuy on 7/6/2006 1:39:07 AM , Rating: 2
I still think this forward compatibitality is in favor of the consumer though... besides the details.... especially if u look at it with the mainstream EYE... like huge companies that decide to upgrade only their cpus... hmm does this ever happen in the real world though?


By Furen on 7/6/2006 1:54:31 AM , Rating: 2
Well, it's great for OEMs too, since current AM2 designs will be able to work with any chips AMD makes in the forseeable future. HT3 is not a huge benefit for single-socket (maybe even dual-socket) sytems, and OEMs will have the choice of dropping the same AM3 chips into cheapo DDR2 systems or high-end DDR3 systems, just like on the Intel side.


By Wwhat on 7/6/2006 9:48:17 AM , Rating: 2
You forget AMD's new HT-socket for addoncards for the HT bus, which means it needs bandwidth/lanes (and a new mobo).



If it is so simlar, why call it AM3?
By KHysiek on 7/6/2006 2:16:23 AM , Rating: 2
I don't get it.


RE: If it is so simlar, why call it AM3?
By Furen on 7/6/2006 2:21:47 AM , Rating: 2
Because it can also work with DDR3 and HT3, in addition to DD2 and HT 1.5.


By Tsuwamono on 7/6/2006 8:36:28 AM , Rating: 2
faster CPUs aswell i heard.


By mendocinosummit on 7/6/2006 10:29:31 AM , Rating: 2
I doubt that AM3 will be compatible with AM4. AM4 will most likely be LGA. At least it should be. AMD needs to unify its production even more to save money.


AM2 / AM3 compatibility
By xenon74 on 7/6/2006 2:40:22 AM , Rating: 2
quote:

...AMD has revealed that AM2 will accept AM2 or AM3 CPU packages...

and
quote:

There is no word yet on the number of pins the new socket will require, but since AM2 sockets are forward compatible with AM3 CPUs, we can at least deduct that AM3 will have fewer than 940 pins.


Are you deducting a socket that will have the same pin layout as AM2 CPU's but not the same pin count as AM2?




RE: AM2 / AM3 compatibility
By Furen on 7/6/2006 2:51:57 AM , Rating: 2
It can fit the socket but it could have one less pin, for example, to make sure that AM2 chips do not fit socket AM2.