Originally posted by: Xajel
AMD already tried this with 4x4 and it wasn't that successfull for several reasons ( based on old arch., ECC required, expensive, limited mobo support ) so I don't think they will make it again...
The QuadFX/4x4 was a flop mostly because of Windows XP's shortcomings and idiot benchmarkers who had obviously never used anything remotely resembling the 4x4 before. The 4x4 was basically an overclockable Opteron 2200 setup and thus used NUMA for handling memory allocation like all other multi-socket Opteron setups. Windows XP has very poor support for NUMA thread scheduling and bounces threads between CPUs and forces a bunch of remote memory accesses, reducing performance. The idiot reviewers didn't know to turn on NUMA node interleaving to automatically stripe memory data between the two nodes to mostly alleviate the performance hit of Windows XP's horrible NUMA support. Thus, you got situations where programs ran much faster with only one FX-70 installed instead of two, since the second CPU being installed activated NUMA and you got the threads bouncing between CPUs and racking up remote memory accesses.
The rest of the issues you list are either only minor reasons or flat-out wrong. The 4x4 did NOT require special memory; it used standard unbuffered desktop memory.
I also think you are confusing registered memory with ECC memory. Registered memory is what servers used to require and is not interchangeable with unbuffered (non-registered) memory as it has different signal and electrical characteristics. Desktops cannot use registered memory, they only use unbuffered memory. ECC is an optional feature that can be implemented on either registered or unbuffered memory. ECC is an optional feature on RAM that can be ignored if not supported by the CPU/chipset and turned off if you want to. You can freely mix ECC and non-ECC RAM of similar types and it will run. You cannot "turn off" anything to use registered memory in a system that only supports unbuffered memory.
Desktop memory is always unbuffered memory and is usually non-ECC since non-ECC memory modules are slightly less expensive. You can use either unbuffered non-ECC memory or unbuffered ECC memory in your desktop motherboard and it will work the same. If you are running a CPU that does not recognize ECC functions like the Intel Core i-series, the ECC functions will be ignored and your ECC memory will run like non-ECC memory. If you run a CPU that does recognize ECC functions like most AMD desktop CPUs and all server chips, it will be able to use the ECC functions in the ECC memory unless you go into the BIOS and tell it not to, then it that case it will ignore the ECC and function like non-ECC memory.
Server memory typically was always registered memory, since the register buffering allowed for greater memory capacities to be used. All registered memory being sold and ECC since it's a server and ECC adds to stability, but you could make registered non-ECC memory if you wanted to and it would work in those servers.
If you want more, then having some single socket G34 mobo will be better option if AMD will make a desktop version of Magny-Cours, this will allow 12 - 16 cores CPU in single socket configuration..
AMD will not make a desktop version of the Socket G34 CPUs. There are single-socket G34 boards like the Supermicro H8SGL that you can use as desktop motherboards, but they are server boards and lack things like a forest of USB ports, onboard sound, PCB colors other than green, and any overclocking ability.
and AMD should drop the ECC requirement too along with making the chip faster and cheaper than it's server version...
The Magny-Cours Opterons as well as the four and six-core Opteron 4100s no longer require registered server memory. They can run on unbuffered desktop memory or
registered server memory. I run mine with unbuffered memory since it's less expensive and faster than registered memory.