Re: A new, unstable system, HW problem ???
On Wed, Apr 27, 2005 at 10:36:01PM -0700, Chris Wakefield wrote:
> This is a by-the-way regarding RAM modules.
>
> I have a K8V deluxe and I'm sure I read somewhere last year that you lose some
> functionality by filling all 3 mem slots as opposed to just the first two.
> It was something about the speed of the RAM being slowed somewhat for some
> reason....Do you recall this or know about this?
As far as I am aware, if you use more than two slots you must drop to
333Mhz speed. I believe it's a limitation of the memory controller
(basically running too many loads on one memory bus means it has to run
slower to work reliably). Socket 939 boards have two memory controllers
and can hence run 2 dimm's per bus (4 total) at full speed, although
there are probably some limitations on those modules too in some cases.
Servers get around this by using registered (buffered) memory which
avoids the bus load issues (but also introduces more delay in accessing
memory so you loose a bit of speed to gain much higher memory limits).
This is why opterons can run 8 or 16 dimms per cpu.
Len Sorensen
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