4gb (4 memory sticks) at 400Mhz on socket 939 MB -- JEDEC specifications ...

[Bryan J. Smith]

On Sat, 2006-07-08 at 15:33 -0500, Mohamad Al-Saqer wrote:
> most motherboards support registered memory.

Remember, the memory controller and channels are on the processor in AMD
Athlon 64 / Opteron.

AMD _only_ supports _unregistered_ on Socket-939.
And AMD _only_ supports _registered_ on Socket-940.

Now there are some claims that some Socket-940 processors will,
unofficially, work with unregistered DIMMs.  But I haven't seen it
personally.

Going the other way, I don't think registered works with any Socket-939
processor at all.  I certainly have not heard anyone doing that.

> Does this mean if ECC non-buffered memory sticks

Umm, that's _unregistered_.  Did you mean registered?
[ BTW, ECC does _not_ matter when it comes to signaling ]

> is installed on 939 MB we get around these limitations?

You can only use unregistered on Socket-939.

At DDR400, that's 1 DIMM per channel, so maximum 2 DIMMs.
At DDR333, that's 2 DIMMs per channel, so maximum 4 DIMMs.

Expect any unstable system if you do otherwise.

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