The speed increase is the word from AMD and like I said the specs seem to bear it out. As far as 4x4, I don't care which socket but they have to let it use nonECC as that is a MAJOR expense.
I wonder if Socket F's Register DDR2 memory controller is also backwards compatible with unregistered DDR2 memory. Otherwise they would have to design a separate chip which isn't very convenient. Opteron 1xxx which use unregistered DDR2 are use AM2 not Socket F so they don't really have an example of that yet.
I load more than 2GB RAM at times and I need something that won't choke. When I go over to Server 2003 x64, I will load it even more. i hope that the FSB won't cause problems when overloading the physical RAm but FSB is uni-directional IIRC and for 4x4 disk IO will go over the South Bridge and memory IO won't. That may turn out to be huge.
At least for us megataskers.
In terms of disk IO, 4x4 isn't a saviour either. In Kentsfield's case, both processors are just 1 hop from the NB. However, in 4x4s case, the second chip is 2 hops away having to go through HT to the 1st chip and then HT again to the NB. That adds latency and even worse, differential latency between the chips.
Similarly, in terms of memory bandwidth through 2 IMCs, if it happens that the 1st chip needs data that is stored in the 2nd chips memory banks it'll have to go over HT to get it. That adds latency and also starves the 2nd processor of bandwidth needed to access the NB. People call for "true" multithreading, but in the event that 4 cores are running a single program this problem is actually increased since each core will need data from each other's memory banks more frequently. In this case, 2 or 4 completely separate programs each having a dedicated chip and it's memory banks would be better at avoiding conflict.
Both 4x4 and FSB have their inherent problems. So we'll have to see. I guess a factor is also the cost of 4x4. It is definitely looking more expensive as a complete system than Kentsfield right now. If 4x4s price is too high, Cloverton may become another option in addition to the cheaper Kentsfield.
4x4 can be directly compared to Opteron 2xx. That doesn't have any bottleneck issues that have been exposed. According t the 4x4 specs each chip has it's own RAM. WIth NUMA, WIndows can put data closer to the correct processor.
They have said that 2 chips would be less than Kentsfield (not the fastest two) but the FX 7000 will probably come in around $400. I think that the reason for using an engineering sample is to disable the ECC pin of SOcket F. There are no two sockets AM2 mobos, so I guess they found it easier to remove the ECC pin than to add dual socket functionality to AM2.
They would be fools to use ECC for an enthusiast product. I expect the mobo to only have PCI\PCIe.
Again I think it will be close between the two but Barcelona will be in another league.(IMO)
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