AMD 4X4 - what is it really, and how does it work?

It would not surprise me if people found the announcement of 4X4 confusing.

I mean read this:

"Advanced Micro Devices Inc. (AMD) launched a four-core chip platform for video gamers Thursday, continuing to battle Intel Corp. for buzz in the high-end "enthusiast" segment."

That was from IDG News.

Now would it not have been simpler to say "AMD introduces dual CPU motherboard for gamers"?

Since there is a significant lack of hard information, I will indulge in some educated guesses - speculation if you will.

I've long suspected that socket 939 and socket AM2 processors would be capable of SMP operation; I mean Opteron's use just one more pin and the 8xx series have three Hypertransport channels; the 2xx series supposedly have two, and the 1xx (and Athlon's) are supposed to only have one.

Note I said "supposed to only have one".

As most of you know, Nvidia (and ATI) often differentiate products by disabling a number of pipelines, pixel shaders etc., and essentially sell the same GPU (granted at different clock speeds, with different speed memory) for very different prices.

AMD and Intel do the same thing by disabling parts of L2 caches, and by limiting multipliers.

Should it really surprise us that socket 939 may be capable of dual processor operation?

Frankly it is likely only a matter of laying out a board with the appropriate 2xx series opteron style interconnect between the two processors and BIOS support.

It looks like with Conroe breathing down its neck, and the K8L still being an unknown factor, AMD is responding by "allowing" SMP with Athlons. Even if we grant that Conroe may be 20%-30% faster for gaming than a single dual core Athlon... with multi-threaded games it would lose to TWO dual core Athlons.

I think this is a smart move.

If the X2 prices drop, and dual motherboards are not significantly more expensive than single socket motherboards, there is great room for performance improvement.

Think about it.

Each socket will still have two memory channels (it would be silly of AMD to only use the memory controller on one of the processors, as using both would give it far higher memory bandwidth than Conroe can get). Using PC6400 DDR2, such a configuration could theoretically approach 25.6GB/sec of aggregate memory bandwidth.

Each socket could connect to a Northbridge. True dual 16X PCIe. Heck, if they use the "daisy chained Southbrige for second PCIe 16x slot" approach, a board could have FOUR 16x PCIe slots. Now if you have a 1KW power supply handy, and Nvidia drivers support it... you chould theoretically have FOUR dual GPU cards, for eight way SLI. In theory.

I could go on, but to see what would be possible, just go take a look at the dual processor Opteron motherboards.

Now... if I wanted to go further out on a limb... why did they call it 4X4, and why are they so close-mouthed?

Hmmm.

AMD is known to be working on four core processors.

Socket 939/AM2 may be capable of three Hypertransport links - we know socket 940 is.

Four socket Opteron motherboards exist, with with two memory channels per socket.

Lets see... 4 sockets X 4 cores... 4X4 makes sense now, does it not?

This would let AMD capture the minds of gamers who have been wanting an answer to Conroe.

This would not require designing a new core, however I am sure AMD is working on K9 and K10 designs again.

This could be brought to market quickly.

It makes sense.

Will it happen?

Heck if I know.

I'm just speculating based on news I've read, and what I know about existing AMD products, and what AMD could do if it wanted to.

The downside for AMD?

It will somewhat cannibalize their server offerings, or to be more specific, it will make it more difficult for AMD to charge a large premium for Opteron 2xx and 8xx parts over Athlons.

But there are signs AMD is willing to do that... the price of the 265 dual core opteron is very close to the price of the 3800x2.

Overall, this would be a win for AMD. Selling more processors, up to four times as many, to a MUCH larger market than servers.

And ofcourse, AMD can always charge a premium for upcoming socket F parts.

UPDATE

After looking at AMD's slides from their analyst day yesterday, it seems that Tomchu was right, 4X4 is just four cores (two sockets) and four GPU's... to be followed a year later by 4X4+ which is eight cores four GPU's (two quad core processors).

I guess I'm greedy, I'd still prefer four sockets :)