[Pc_Support] Memory Technology and Chip Select -- WAS: Rules-of-thumb on upgrading components for an older mainboard ...

[Bryan J. Smith]

On Sat, 2006-09-23 at 01:48 -0400, Bryan J. Smith wrote:
> No, not at all.  There are 2GB and 4GB DIMMs.
> And registered DIMMs allow you to use twice as many.
> E.g., a single Socket-940 Opteron can actually support 32GiB in 8 DIMM
> slots.  A single Socket-939 Athlon 64 can actually support 16GiB in 4
> DIMM slots.

Okay, that was for DDR333/PC2700.

But still, for DDR400/PC3200, a single Socket-940 Opteron can support
16GiB in 4 DIMM slots, and a single Socket-939 Athlon 64 can support
8GiB in 2 DIMM slots.

Yes, you can now only use 1 (2 if registered) DIMMs per DDR400/PC3200
channel or any DDR2/PC2-3200+ per JEDEC specifications.  But that has
_nothing_ to do with the _size_ of the memory.

It has to do with the _number_ of DIMMs.
DDR2/PC2 is 1 DIMM per channel.
DDR400/PC3200 is 1 DIMM per channel.

2GB unbuffered DDR400 DIMMs exist in commodity now.
4GB registered DDR400 DIMMs have been available for some time too.


-- 
Bryan J. Smith          Professional, technical annoyance
mailto:b.j.smith at ieee.org    http://thebs413.blogspot.com
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