Asus Claims Certain  Boards AM3+ Compatible, Says Zilch About Bulldozer

Asus Claims Certain Boards AM3+ Compatible, Says Zilch About Bulldozer

One downside of the upcoming Phenom II - Bulldozer transition is that the new processors won't be compatible with current AM3 motherboards. This news disappointed certain AMD enthusiasts, given that Sunnyvale typically focuses on chipset longevity, but the company justified the mood by stating that the only way to fully exploit the power of Bulldozer's core was to switch to a new socket--AM3+.

A recent announcement from Asus has thrown a wrench into this scenario. We've reached out to both Asus and AMD for additional information; neither has gotten back to us as of this writing.

Asus' website states:
Current owners of an 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... Current ASUS 890FX and 890GX series motherboards can be upgraded to enjoy the extra performance offered by future AM3+ CPUs (emphasis added). ASUS will also be releasing*** the AMD 8-Series Chipset motherboards based on 880G and 870 as well as the 760G Chipset on the AM3+ socket for increased selection so users can enjoy AM3 and AM3+ CPUs.

** Current BIOS update is a beta release. Please check the ASUS support site for continual updates.
There's precious little wiggle room in Asus' statement and there's no way the company could be referencing Llano—that chip, when it appears, will use AMD's Socket FM1. The state of AM3+ CPU support in existing motherboards has never been less clear. Up until now, the preponderance of evidence suggests that the AM3+ socket is physically different from the AM3 socket.


That's AM3 on the left, AMD3+ (purportedly) on the right. Original photographer unknown.

Look at the stanchion that's circled in both images. The AM3 socket blocks off two pins while the AM3+ socket blocks off just one pin. In theory, this explains why AM3 chips can work in AM3+ motherboards but not vice versa.

One of the motherboards Asus' lists as supporting AM3+ is the Crosshair IV Extreme. We recently reviewed that board, noting that "If existing AM3 products were Bulldozer-compatible and LucidLogix's game support was more mature, this motherboard would be a must-have for any AMD enthusiast..."

Actual Bulldozer support on the Crosshair IV Extreme would be a Very Big Deal, but a quick check of our testbed proved that the board isn't harboring an AM3+ socket in disguise.


The Crosshair IV Extreme's CPU socket. Note that the space in the upper-right-hand corner blocks off two pins, not one

Check the upper-right corner (outlined in violet) and you'll see that the gap is sized for an AM3 rather than an AM3+ processor. With AMD saying that AM3+ processors won't be supported on AM3 boards, Asus saying it can grant such support in a BIOS update, and a physical difference between the sockets, the upgrade situation has gone murky in less than a week.

Possibilities:

Absent any input from AMD or Asus, we've put together a short list of potential explanations.

Asus never mentions Bulldozer by name on its webpage and refers only to "extra performance offered by future AM3+ CPUs." Back when AMD released its original AM3 processors, a number of manufacturers (including Asus) took to labeling AM2 boards as offering AM3 support. We know AMD will continue to sell Phenom II processors after Bulldozer launches; Asus may simply be noting that an AM3+ Phenom II will fit into an AM3 socket without referring to Bulldozer at all. At present this seems the most likely scenario--it explains why Asus doesn't mention Bulldozer on its announcement page. Unfortunately it also invites confusion—AM3+ Phenom II's would end up working in AM3 boards while AM3+ Bulldozer's would be restricted to AM3+  boards.

Another option is that AMD will release a series of AM3-compatible Bulldozers. The company has done this before—it continued to release Socket 754 chips up through the launch of Socket 939—but AMD also publicly committed to supporting the Socket 754 platform before and after it launched. AMD's John Freuhe is on record at multiple forums stating that AMD will not "support" Bulldozer on AM3, but the word "support" can be quite fluid.

Third, it may be possible to modify a Bulldozer chip (by presumably removing that single extra pin). This would theoretically make Bulldozer pin-compatible with the current AM3 socket and explain why AMD would never support such a configuration. Asus' claim that a board needs nothing more than a BIOS flash to be AM3+ compatible, however, strongly implies no major chip surgery will be required.

Fourth, it's possible that AMD is pulling an Intel with regard to new chipsets. The pin that (presumably) plugs into the now-vacant hole in the upper-right-hand of an AM3+ socket could be relatively spurious; the company might simply want to sell fresh chipsets. . Again, however, this doesn't really track. Asus pointedly notes that it's launching a series of motherboards based on AMD's 880G and 760G chipsets--not something the company could do if AMD's older chipsets weren't capable of detecting and running AM3+ processors.

At this point we're guessing that Asus' is referring to future Phenom II-based products that will launch on Socket AM3+ rather than anything Bulldozer-related. It'd be fabulous if Asus can offer Bulldozer on even some of its AM3 boards, but until the company states that it's explicitly referencing the next-gen processor, we're assuming it isn't. It makes more sense that AMD would move Phenom II to AM3+ the same way it released AM3 versions of AM2+ processors a few years ago.
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Interesting...but i seriously doubt my gigabyte board is AM3+ compatible. Plus wont it make more sense to upgrade to a new chipset? Especially if youre going with something as potent as the new FX series? Guess we'll see what happens come june...

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AMD has never mentioned anything about the pin count on Bulldozer. It's purely speculation on AM3+ socket motherboards. Yes, the physical AM3+ socket is different with 942 pin contacts.

However, lets look back:

The AM3 Socket has 941 pins contacts. The actual CPU only has 938 pins.

It could be possible that Bulldozer can have upwards to 941 pins and still be compatible with AM3 socket motherboards with a BIOS update. And since AMD has only said they don't officially SUPPORT Bulldozer in AM3 sockets, they have NEVER mentioned ANYTHING about the pin count. Even JF-AMD has mentioned that he does not know the pin count.

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KVJ,

That's why I took the time to talk pin positioning.

Fact: AM3 chips will work in AM3+ sockets.

Fact: AM3+ chips will not be "supported" in AM3 sockets.

Fact: Socket AM3+ must use an extremely similar package layout to AM3, or else AM3 chips couldn't be forwards-compatible.

That brings us right back to the one 'extra' pin socket on the AM3+ boards. Since we know the pin layouts must be mostly identical and we know an AM3+ socket has room for one additional pin (as described above), it's logical to assume a connection between the two.

Put differently, there's no reason *not* to think the presence of an extra pin is why AM3+ CPUs won't fit in AM3 boards (although, as I've already stated, it may be possible to modify the processors themselves).

Edit/Clarification:  You make the point that while there are 941 pins in an AM3 socket, there are not that many pins on an AM3 chip. You're correct--but the explanation you give is the reason I'm right to say a BIOS update won't fix the physical compatibility issue.

It's true that there are two points on an AM3 CPU where a pin *could* connect but don't (the CPU leaves 3 spaces in both cases with only two spaces blocked off on the motherboard.) If you compare Socket AM3 to AM3+, however, you'll note that the *only* difference between them is in the northeast quadrant where a two-block stanchion is now just one block.

If an AM3+ chip uses a pin in that space, non-modded use is out. The only reason we know of that AMD would *remove* a block... is if it intended to put something in there.

I'll agree with you that it's possible that the socket change is meaningless, that AM3+ Bulldozers will plug right into AM3 boards, and that there'll be no need for anything but a BIOS update--but if these are true, you'd think AMD or Asus would be talking about it.

Edit Additional:  Current AM3 boards are "Socket 941."  AM3+ are supposedly "Socket 942."  The only change between the two is that there's an extra pin-hole in AM3+--which again supports our belief that there's something important about that spot. 

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Please make a new article when this becomes clear =) some of us will be in a confused situation once the Bulldozer CPUs comes out. I'm even on a 800series ASUS mobo :P

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All you have to do is drill one little hole,.....

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Realneil,

Uh. No. Not unless we find out that the pin can be removed / left unconnected in the first place. ;)

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Joel H:
RealNeil, Uh. No.

Yeah,.........I was just kidding around Joel.

I much prefer to just buy the right board to begin with. Even if current AM3 boards can be somehow "made compatible" with Bulldozer, The socket and board that it's designed to work with will probably have features and possible technological advances built-in that one would want to be able to enjoy.

Once it's out, I'll try to figure out a way to buy into Bulldozer and see how it really does, for my 'real world' usage.

 

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I just think they will release some Socket AM3 compatible units first, just like the 1st batch of Phenom II 940 which were backward compatible with AM2+ and later were AM3  only.

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No, there will not be an AM3 version of BD coming out later, those processors will be AM3+ only.

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Neo,

What? I tested an AM2+ motherboard with a six-core Thuban 1100T. There were no problems.

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Never mind... my bad. I got confused there for a moment. I was thinking about the DDR2 and DDR3 thing.

The first Phenom II 940's were DDR2 only IIRC.

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but then again someone should go test out realneil's idea :P

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I have been hearing these rumors as well. I just got a fresh msi 890fx board back from RMA... the socket is still white though. Can't wait to see how this pans out.

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LifeSkills,

Socket color is irrelevant. The black *is* probably an attempt to distinguish the two, but what's going to matter is the presence / absence of that single-pin block.

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Any response yet from AMD or ASUS?

You will let us know when , or if they responde won't you?

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i found this from asus site. doesnt specifally say bulldozer.

http://event.asus.com/2011/mb/AM3_PLUS_Ready/

thats what i found

goodluck

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XFactor,

That's the page this article is based on. It's linked above. ;)

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maybe the AM3+ chip won't have the extra pin... That's for the am4 chip to work in the am3+ board???????????????????

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I have no faith that Asus will release BIOS updates supporting newer processors after their motherboards have ceased production and have been sold. Case in point: My original Asus Crosshair is an AM2+ mobo  that won't support the last AM2+ processors produced (Phenom 920 and 940). A modded BIOS supporting these CPU's is available, but it's not from Asus. Once the mobo has passed the product 'lifecycle' Asus kisses it goodbye. The original Crosshair motherboard had a very short lifecycle. 

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I recently updated my Asus M4A89GTD Pro/USB3 to the latest BIOS and the one before was a beta for am3+ support so i am guessing my board is am3+ compatible

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LouisTessier:
i am guessing my board is am3+ compatible

Yes,......as long as it has the proper socket, or they release a Bulldozer CPU that has one less pin.

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