Dear Joe:
I never sait it did. But the core has them. 3 of them in Rev F and G cores, and 4 in Rev H. AMD just chose not to route them to pins (apparently).
Check pin counts. With 940 pins in AM2, where could they have gotten the 106 pins needed for another 16/16 HT interface? And still allowing for seperate power supplies for each core, the XBAR and HT link, and the MCT/DCTs two seperate DDR2 channels. 106 pins are a lot to free up although some could be shared with the other HT link. S1 does have only 638 pins, but it may have only 1 DDR2 channel with lower amounts of power/ground pins due to the 35W TDPmax wrt 120W TDPmax of the desktop AM2. Judging by current requirements, AM2 has to have 3.4 times the total number of power and ground pins of S1. Those two changes could easily save 302 pins. And then there is those pins that will be needed for DDR3 and many other things coming up in the near future. Adding the 267 pins to AM2 to socket F could allow for 2 or 3 additional 16/16 HT links with some sharing.
they could have increased it, but there certainly were enough pins in Socket 939, which AMD just didn't connect.
Again, they needed a bunch for the second completely seperate DDR2 channel. If you look at the old 940 and 939 pin layouts, you can see the large amount of pins taken up by duplicating the control, clock and addressing pins to allow for unbuffered memory in the 939 over that of the 940. The you need to add pins for the higher TDPs of the FXs. And keep a few more spares JIC. After all that, more than 106 pins were used negating one whole 16/16 HT link and part of another. Socket AM2 just uses the same basic layout of 939 but uses a few more of the spares from the second negated HT link for seperate the power planes for up to 4 cores, the section holding the XBAR and HT link and the memory controller section. And a few more for DDR2 to allow the channels to be totally independent.
And there is a cost for more pins in additional layers for the MB, more routing, package size and package cost. That is not trivial for the tens of millions made each quarter. Server and enthusiasts are willing to pay the extra price needed for the extra functionality. If you want all of that, you will have to pay for socket F MBs and all of the associated costs. And because they only connect one HT link, they have three or four chances to find a good one. With all of HT links socket F allows, AMD has to verify that all are good just like they did for socket 940. MB makers could use the other two HT links in 2## Opterons, but few used more than one on one socket.
And if you wait for a few quarters, vendors could make dual and multi AM2+ socket MBs. By that time AMD will still have only three current sockets used by their latest stuff, mobile S#, desktop AM# and server F#. There are two sets of things here and AMD has control of only one until recently. The first set is what is possible in the current designs. The second is what vendors design their boards to actually use of the possibilities. MB makers could have put 6 DIMM slots in 939 MBs, but chose to only put four. They could have put 8 per 940 sockets, but few did like HP's 585. Some could have used 4 HT links for I/O in 2S MBs, but none did. They could have connected the NB and SB chain back to other 2S MB socket for additional reliability, but none did. AMD has to check for everything that is available to be able to be used, but MB and OEM designers may not make use of them.
I am hoping that that AMD has learned from the Socket AM2 f-up (that it had to go to Opteron socket for 4x4) and will not repeat the same mistake with AM3. But my money is on AMD making the same mistake again. Something like 4x4, or Torrenza capability should be available to all AM3 processors.
First AMD didn't F'up with AM2. Intel did another kludge job. And you want the functionality for free instead of having to pay for it. Some of the goes to AMD, but the rest has to go to the various vendors that make use of that as an incentive to provide it. Just like you have to pay more for SLI or Crossfire enabled MB over one that can't. If you can wait for it, many of those things will be available gratis as the luxury becomes basic required functionality by the market. Like the mobile Semprons gaining 64 bit functionality with the AM2 and S1 versions.
As for Samsung going 1Gb and up, good for them. We have been stuck with 512Mb for far too long. There was no good reason for needing DS DIMMs to get 1GB for the last 3 process generations (180nm, 130nm and 90nm, going now to 65nm).
Pete |
