Tanclearas
Senior member
I want to use this thread to collect information about the AM3/AM3+/800-series/900-series mess. Essentially, AMD is holding back information that could have a significant impact on those of us who are ready to make purchases now. What is particularly puzzling is that AMD has released more details about the Bulldozer architecture than they have about the platform it's going to be in.
There has been so much speculation that it has become virtually impossible to distinguish fact from fiction. With a little luck, maybe this thread can draw some attention from AMD and we can get some answers to some very simple questions. We aren't asking for benchmarks. We aren't asking for more details about Bulldozer. All we want is for AMD to help us make a decision about buying AMD motherboards right now.
Below is a summary of the information I have tracked down so far.
The first indication about Bulldozer requiring AM3+ came in September (http://www.xbitlabs.com/news/cpu/display/20100826225852_Desktop_Bulldozer_Processors_Will_Require_New_Platforms_AMD.html)
According to AMD employee JF-AMD (various forums), AMD will not support BD in AM3. Caveats here are that JF-AMD works in servers, not desktops, and there is a difference between "unsupported" and "cannot work".
MSI is implying (http://event.msi.com/mb/am3+/) that there are no limitations related to Turbo Core 2.0, power efficiency, etc, even when using 8-core (from the image at the top even though we know BD is a 4 module part for 8 core), 32nm AM3+ processors with current AM3 motherboards. Unfortunately, it says "AMD AM3+ multi-core processors support Turbo Core 2.0", not that the AM3 motherboards support it.
According to Asus (http://event.asus.com/2011/mb/AM3_PLUS_Ready/), "Current owners of an [Asus] AM3-based board* will make their AMD 8-Series motherboards compatible with the latest AM3+ CPUs with a simple BIOS** update from the official ASUS website."
According to Josh Walrath (JW) from pcper.com (http://pcper.com/article.php?aid=1106), "There will likely be certain tradeoffs with using an AM3 board with AM3+ processors, and these look to be related to power efficiency and maximum turbo clockspeed targets." Unfortunately, this also seems to be speculation, and no sources are quoted. Further, JW states that upcoming "black socket" motherboards (Gigabyte isn't the only company using black sockets for AM3+) are actually AM3 sockets. He says, "From all indications these are not actually AM3+ sockets, but are in fact AM3 but in a black plastic to convey Bulldozer/AM3+ compatibility." This isn't entirely true in that the black sockets (from the various motherboard makers) have a different pin (or hole) count from the standard white AM3 sockets. Physically, they are different, so perhaps JW is trying to say that these are AM3 sockets electrically.
Related to all of this is the discussion of 800- vs 900-series chipsets. The latest chart I have found detailing and comparing the chipsets is at http://www.amdzone.com/phpbb3/viewtopic.php?f=52&t=138146&start=2. Despite these charts, the 900-series chipset is supposed to use HT 3.1, although I haven't yet found official confirmation of that. In looking for differences, the 900-series chipsets seem to include IOMMU support which was previously only found in the 890FX. Interestingly, according to one chart, 890FX and 990FX are feature-identical except for the southbridge pairing and the TDP. Comparing the southbridges that get paired with 890FX (SB850) and 990FX (SB950), the only difference seems to be two additional PCIe x1 on SB950.
The other recent chipset-related announcement (not official) is that the 900-series chipsets will support Nvidia's SLI.
So, will the 900-series chipset actually provide any BD-specific advantages?
What I am hoping for is a definitive response indicating which of the following statements/scenarios is true.
Note that for points 3 and 4 (and now 5), I am not referring to non-CPU-specific features such as SLI.
I can update this post if people provide other sources of information that are different from what is above (not just different links to the same information). Also, I can update the statements above if there is a sense they aren’t clear enough.
Update 1: It appears that a combination of options 2 and 3 is the most likely right now. http://www.overclockers.com/amd-confirms-support-bulldozer-am3/?utm_source=pr (thanks busydude!). Unfortunately, overclockers.com simply stated that this information came from "an interview with AMD". I don't really know what that means. Who is "AMD"? Is there a transcript of the interview? Finally, if Scorpius is backward compatible with AM3, what is AMD waiting for?
Update 2: The overclockers.com interview was with Damon Munzy (thanks hokiealumnus!). It would seem that Josh Walrath was correct about the black socket motherboards still being "AM3" even though the physical socket looks like AM3+. It appears that AMD only considers true AM3+ to be the physical socket combined with a 900-series chipset (this combination is Scorpius), and that platform is likely to be required to "support new power management features as well as “boosting technology” (turbo boost)".
Update 3: Added another point to the list above. Also, HyperTransport (HT) 3.1 specification was released August, 2008, and many people believed it would show up in the 800-series chipset (and even 700-series). According to the HyperTransport Consortium, "HyperTransport 3.1 maintains the same advanced architectural, power management and protocol features of HyperTransport 3.0." So, even if the 900-series chipsets does feature HT 3.1, it doesn't appear as though that is what will enable any special features of BD.
Update 4: To pick out an important bit from the overclockers.com interview:
Update 5: AsRock has created a page (http://www.asrock.com/news/events/2011AM3+/) explaining why their boards are "real" AM3+ boards. There are some interesting bits of information there, and could potentially make scenarios 3, 4, and 5 (note that 3 is a sub-set of 5) all to be true, depending on the design of the motherboard. If the information on AsRock's page is indeed accurate, it just makes it that much stranger that AMD wouldn't have released this information publicly.
Update 6: The 900-series chipsets will get SLI support from Nvidia. http://blogs.nvidia.com/2011/04/you-asked-for-it-you-got-it-sli-for-amd/ This doesn't really have anything to do with BD support on existing AM3 or 800-series boards, but it is a distinguishing factor between the 800- and 900-series chipsets.
Update 7 (May 30, 2011): The following is from Anandtech.
Source: http://www.anandtech.com/show/4365/computex-2011-asrock-llano-990fx-and-z68-motherboards
There has been so much speculation that it has become virtually impossible to distinguish fact from fiction. With a little luck, maybe this thread can draw some attention from AMD and we can get some answers to some very simple questions. We aren't asking for benchmarks. We aren't asking for more details about Bulldozer. All we want is for AMD to help us make a decision about buying AMD motherboards right now.
Below is a summary of the information I have tracked down so far.
The first indication about Bulldozer requiring AM3+ came in September (http://www.xbitlabs.com/news/cpu/display/20100826225852_Desktop_Bulldozer_Processors_Will_Require_New_Platforms_AMD.html)
"The existing G34 and C32 server infrastructure will support the new Bulldozer-based server products. In order for AMD’s desktop offering to fully leverage the capabilities of Bulldozer, an enhanced AM3+ socket will be introduced that supports Bulldozer and is backward-compatible with our existing AM3 CPU offerings," an official from AMD said in an interview with Planet3DNow web-site.
Apparently, it was possible for AMD to make Bulldozer microprocessors compatible with existing AM3 infrastructure, but in order to do that, the company would have to sacrifice certain important features of the new core.
"When we initially set out on the path to Bulldozer we were hoping for AM3 compatibility, but further along the process we realized that we had a choice to make based on some of the features that we wanted to bring with Bulldozer. We could either provide AM3 support and lose some of the capabilities of the new Bulldozer architecture or, we could choose the AM3+ socket which would allow the Bulldozer-base Zambezi to have greater performance and capability," the official said.
If someone can identify the original source, including who "the official" from AMD is, that would be helpful.Apparently, it was possible for AMD to make Bulldozer microprocessors compatible with existing AM3 infrastructure, but in order to do that, the company would have to sacrifice certain important features of the new core.
"When we initially set out on the path to Bulldozer we were hoping for AM3 compatibility, but further along the process we realized that we had a choice to make based on some of the features that we wanted to bring with Bulldozer. We could either provide AM3 support and lose some of the capabilities of the new Bulldozer architecture or, we could choose the AM3+ socket which would allow the Bulldozer-base Zambezi to have greater performance and capability," the official said.
According to AMD employee JF-AMD (various forums), AMD will not support BD in AM3. Caveats here are that JF-AMD works in servers, not desktops, and there is a difference between "unsupported" and "cannot work".
MSI is implying (http://event.msi.com/mb/am3+/) that there are no limitations related to Turbo Core 2.0, power efficiency, etc, even when using 8-core (from the image at the top even though we know BD is a 4 module part for 8 core), 32nm AM3+ processors with current AM3 motherboards. Unfortunately, it says "AMD AM3+ multi-core processors support Turbo Core 2.0", not that the AM3 motherboards support it.
According to Asus (http://event.asus.com/2011/mb/AM3_PLUS_Ready/), "Current owners of an [Asus] AM3-based board* will make their AMD 8-Series motherboards compatible with the latest AM3+ CPUs with a simple BIOS** update from the official ASUS website."
According to Josh Walrath (JW) from pcper.com (http://pcper.com/article.php?aid=1106), "There will likely be certain tradeoffs with using an AM3 board with AM3+ processors, and these look to be related to power efficiency and maximum turbo clockspeed targets." Unfortunately, this also seems to be speculation, and no sources are quoted. Further, JW states that upcoming "black socket" motherboards (Gigabyte isn't the only company using black sockets for AM3+) are actually AM3 sockets. He says, "From all indications these are not actually AM3+ sockets, but are in fact AM3 but in a black plastic to convey Bulldozer/AM3+ compatibility." This isn't entirely true in that the black sockets (from the various motherboard makers) have a different pin (or hole) count from the standard white AM3 sockets. Physically, they are different, so perhaps JW is trying to say that these are AM3 sockets electrically.
Related to all of this is the discussion of 800- vs 900-series chipsets. The latest chart I have found detailing and comparing the chipsets is at http://www.amdzone.com/phpbb3/viewtopic.php?f=52&t=138146&start=2. Despite these charts, the 900-series chipset is supposed to use HT 3.1, although I haven't yet found official confirmation of that. In looking for differences, the 900-series chipsets seem to include IOMMU support which was previously only found in the 890FX. Interestingly, according to one chart, 890FX and 990FX are feature-identical except for the southbridge pairing and the TDP. Comparing the southbridges that get paired with 890FX (SB850) and 990FX (SB950), the only difference seems to be two additional PCIe x1 on SB950.
The other recent chipset-related announcement (not official) is that the 900-series chipsets will support Nvidia's SLI.
So, will the 900-series chipset actually provide any BD-specific advantages?
What I am hoping for is a definitive response indicating which of the following statements/scenarios is true.
- AM3 socket will not work with Zambezi.
- AM3 socket can work with Zambezi (dependent on motherboard manufacturers).
- AM3+ socket with 800-series chipsets will work with Zambezi, but will not support all CPU-specific features.
- AM3+ socket with 800-series chipsets will support Zambezi, including all CPU-specific features (dependent on motherboard BIOS, power, etc implementation).
- New: AM3/AM3+ sockets used with 800-series chipsets will work with Zambezi, but will not support all CPU-specific features (power efficiency and Turbo Core 2.0).
Note that for points 3 and 4 (and now 5), I am not referring to non-CPU-specific features such as SLI.
I can update this post if people provide other sources of information that are different from what is above (not just different links to the same information). Also, I can update the statements above if there is a sense they aren’t clear enough.
Update 1: It appears that a combination of options 2 and 3 is the most likely right now. http://www.overclockers.com/amd-confirms-support-bulldozer-am3/?utm_source=pr (thanks busydude!). Unfortunately, overclockers.com simply stated that this information came from "an interview with AMD". I don't really know what that means. Who is "AMD"? Is there a transcript of the interview? Finally, if Scorpius is backward compatible with AM3, what is AMD waiting for?
Update 2: The overclockers.com interview was with Damon Munzy (thanks hokiealumnus!). It would seem that Josh Walrath was correct about the black socket motherboards still being "AM3" even though the physical socket looks like AM3+. It appears that AMD only considers true AM3+ to be the physical socket combined with a 900-series chipset (this combination is Scorpius), and that platform is likely to be required to "support new power management features as well as “boosting technology” (turbo boost)".
Update 3: Added another point to the list above. Also, HyperTransport (HT) 3.1 specification was released August, 2008, and many people believed it would show up in the 800-series chipset (and even 700-series). According to the HyperTransport Consortium, "HyperTransport 3.1 maintains the same advanced architectural, power management and protocol features of HyperTransport 3.0." So, even if the 900-series chipsets does feature HT 3.1, it doesn't appear as though that is what will enable any special features of BD.
Update 4: To pick out an important bit from the overclockers.com interview:
That was contrary to my previous understanding that an extra pin on the Zambezi processors would be positioned in a manner to prevent a user from installing an AM3+ CPU into an AM3 socket.
Update 5: AsRock has created a page (http://www.asrock.com/news/events/2011AM3+/) explaining why their boards are "real" AM3+ boards. There are some interesting bits of information there, and could potentially make scenarios 3, 4, and 5 (note that 3 is a sub-set of 5) all to be true, depending on the design of the motherboard. If the information on AsRock's page is indeed accurate, it just makes it that much stranger that AMD wouldn't have released this information publicly.
Update 6: The 900-series chipsets will get SLI support from Nvidia. http://blogs.nvidia.com/2011/04/you-asked-for-it-you-got-it-sli-for-amd/ This doesn't really have anything to do with BD support on existing AM3 or 800-series boards, but it is a distinguishing factor between the 800- and 900-series chipsets.
Update 7 (May 30, 2011): The following is from Anandtech.
So it seems as though SLI support (if motherboard manufacturer licenses it) is the only distinguishing factor between 800- and 900-series chipsets. This isn't really new information, but rather further confirmation of the guesses previously made.
Source: http://www.anandtech.com/show/4365/computex-2011-asrock-llano-990fx-and-z68-motherboards
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