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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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RE: AM2 Motherboard Royally Screwed Over
By defter on 7/6/2006 6:31:27 AM , Rating: 4
quote:
All KT133A are compatible with Athlon XP.


That's not true, see here for example:
http://www.xbitlabs.com/news/other/display/news145...

"Our tests revealed the following. As it had been promised, KT7A rev. 1.3 turned out absolutely compatible with Athlon XP CPUs. It worked well with the older as well as with the newer BIOS versions, with that only difference that the older BIOS detects the wrong CPU type considering it an Athlon 4 instead of Athlon XP.
KT7A revision 1.0 failed to boot with Athlon XP CPU, i.e. it didn’t even start the POST. When we reflashed the s5s BIOS intended for mainboards rev. 1.3, the situation didn’t get any better."

and

"And here are some comments of ABIT’s Techsupport on the matter:
"We do understand that the owners of KT7A/KT7A-RAID (1.0, 1.1, 1.2) are a bit upset with the incompatibility of their mainboards with Athlon XP processor. We launched these mainboard revisions before AMD provided us the official specifications of the Athlon XP CPU launched on October 9. To tell the truth, we started producing revision 1.2 in May. So, we turned out unable to guarantee that the older mainboard revisions would support Athlon XP. Unfortunately, this is hardware problem and it cannot be eliminated via BIOS update."


quote:
Don’t forget Intel each time that has to change its memory support from:

DDR266 -> DDR333 -> DDR400 -> DDR2 400 -> DDR2 400/533 -> DDR2 667 -> DDR2 800


Two comments:
1. Intel's first dekstop DDR2 chipset supported borth DDR2-400 and DDR2-533 so you should remove "DDR2 400" from your list.
2. It's natural that supporting faster memory requires different chipset. However its optional, in most these cases you could still use new CPUs even though the motherboard supported only older memory.


quote:
AMD (K8):

DDR266/333/400/... -> DDR2 400/533/667/800/...

Just requires 2 chipsets (motherboards), 2 processors.


Well, the K8 was launched months AFTER DDR-400 spec has been finalized... Still first versions of Athlon 64 DIDN'T support DDR-400 with two double sided DIMMs per channel. This support was added in the later stepping.

You also forgot that there are four (not two) different sockets for desktop Athlon64: 940, 939, 754 and AM2. For example owners few first Athlon64 FXs have no choice but to replace their motherboards if they want to upgrade (unless they want to get very expensive Opteron 2xx).


By nserra on 7/6/2006 9:23:46 AM , Rating: 2
defter,

I put -> DDR2 400/533 ->
in the same line because of that.

I have a very old KT133A (DFI) and worked fine.
My friends others, Chaintec, ECS, ... some say Athlon4 or Athlon MP, but works. There is one with Via KT133 (100Mhz FSB) works great at 120Mhz bus (Gigabyte) and detects Athlon XP.
I believe in you, some work other not, but I bet is 98%, 2%. Just look what ASROCK they put some chipsets working with processors that Intel say doesn’t work. Conroe on 865G?
http://www.asrock.com/product/775i65G.htm

Right K8 was launched after DDR400, and AMD2 was launched before DDR2 800 and DDR2 1066.

I think socket 940 where only assigned to FX and Opteron so doesn’t really count as desktop (0,001% of the desktops).

And from the same link you provided:
VIA KT133A is fully compatible with Athlon XP CPUs.
Many KT133A based mainboards from other manufacturers (independent of the revision number) work fine with Athlon XP.
Athlon XP processor uses the same Socket A physical interface as the regular Athlon (Thunderbird) does, that is why lame excuses of ABIT’s representatives about the lack of the final Athlon XP specs look very unconvincing. Especially, since AMD-760 based mainboards, which appeared even before those on KT133A (we don’t mean the awfully long delayed ABIT KG7), do not have any problems working with Athlon XP processors, and it means that the final processor specs have nothing to do with it.


By Samus on 7/6/2006 2:41:39 PM , Rating: 2
Strange, I never had a problem running a Athlon XP 3200+ at 2.2GHz (overclocked from 2GHz) in a KT133A at 133mhzfsb x 16.5 I think, manually adjust voltage to 1.8v.


"I modded down, down, down, and the flames went higher." -- Sven Olsen

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