A8N-SLI - 3 DIMMS

[edde]

I currently have been running an A8N-SLI Deluxe system for months now with
no problems.
I currently have 2x512MB OCZ PC3200 EL Dual Channel memory.

I do alot of image editing, and now with Photoshop CS2, 1GB is just not
cutting it. The expensive solution would be to sell my dimms, and buy 2x1GB
PC3200 EL Dual Channel memory.

However, could I just buy 1 more dimm of 512MB or 1GB memory and put it in
the third slot? I know that running 4 dimms can sometimes cause problems, or
force you to use slower timings, but would running 3 dimms as above be
problematic at all?

 

[Paul]

I currently have been running an A8N-SLI Deluxe system for months now with
no problems.
I currently have 2x512MB OCZ PC3200 EL Dual Channel memory.

I do alot of image editing, and now with Photoshop CS2, 1GB is just not
cutting it. The expensive solution would be to sell my dimms, and buy 2x1GB
PC3200 EL Dual Channel memory.

However, could I just buy 1 more dimm of 512MB or 1GB memory and put it in
the third slot? I know that running 4 dimms can sometimes cause problems, or
force you to use slower timings, but would running 3 dimms as above be
problematic at all?

S939 is not really dual channel. In AMD parlance, the system
operates in 64 bit memory mode, or 128 bit memory mode. Think
of it as a narrow single channel, or a wide single channel.

See page 14 of this doc:
http://www.amd.com/us-en/assets/content_type/white_papers_and_tech_docs/31411.pdf


When in 128 bit mode, the only valid configurations are
two DIMMs or four DIMMs. The channel width must be maintained,
and once you decide to go "wide channel", the DIMMs have to
be installed as functional pairs.

Three DIMMs would mean that the third DIMM would be missing
its partner. The processor would attempt a 128 bit access, and
64 bits of that would be driven by "air".

Why not just buy 2x512MB DIMMs _exactly_ like the ones you've got.
You can run them DDR333 command rate 1T or DDR400 command rate
2T (this assumes a CG stepping or later processor, as I seem to
remember some mention of the command rate option only being
implemented on later processors). And by the way, I'm not
kidding about the "exactly" part - there have been what
appear to be BIOS problems, with using two pairs of DIMMs that
don't have the same SPD contents on the DIMMs:

http://groups.google.ca/[email protected]

The DDR400 2T setting will give slightly more performance than
DDR333 1T. At least one poster here reported that as the
result of his testing.

Selling your DIMMs and buying 2x1GB is certainly an option, as
then you might be able to get more performance from the RAM. It
all depends on how much more money you have to splash around, for
that little bit of extra memory bandwidth.

HTH,
Paul

 

[edde]

Thanks for the detailed explanation.
The reason I dont want 4 dimms is because, as you stated, you have to run
your memory at reduced settings.
I would rather run 3 dimms at full settings. But, the ideal solution is
always the costliest. Sell my ram, and get 2x1GB dimms.

 

[paul berry]

On Fri, 29 Apr 2005 17:05:39 -0500, "edde"

I have an a64 board, the a8v deluxe rev 2. Im using all 4 dimms on my
board running 4x 256mb PC3200 ddr400 ram at full speed with no
problems at al.

 

[edde]

Are you running 1T or 2T memory settings?
From what I understand if you use all dimms, you must use only 2 T.