I have 2x1GB DIMMs of Crucial Ballistix memory installed on my A8N-SLI
Deluxe, and I'm looking for a bit more to ease some Photoshop work I'm
doing. I'd like to add 2 more 1GB DIMMS, but my understanding is that I'll
only be able to realize ~2.75GB total due to some BIOS issue. In fact, the
Crucial web site even makes the disclaimer" "Important information about
your system. Although the memory can be installed one module at a time, the
best performance comes from using matched pairs of modules. Although the
nForce 4 chipset supports 4GB of memory, Windows and the BIOS will usually
see 2.75-3GB when 4GB is installed. This is due to limitations in memory
addressing by the BIOS."
Is this destined to be a perpetual issue, or can add 2 more 1GB DIMMs and
hope that the issue is resolved in future BIOS releases? I'm currently
running 1006.
These are the release notes for the 1006 BIOS:
[ 1006 ]
1. Fixed after resuming from S3, the CPU multiplier and CPU clock
will be restored to default value if user overclock.
2. Fixed show wrong device (ZIP) on summary screen when PATA
controller was disabled. It should show 'None'.
3. Change the CHIP fan fail threshold RPM to fix sometimes POST
will wrong show CHIP Fan fail Msg.
4. Update A8N-SLI Deluxe Logo.
5. Add Memory Re-map function SETUP Item.
The last item, item #5, notes that a new setting has been added
to the BIOS interface. The BIOS was missing the necessary setting
to handle configurations with large memory installed.
While some of the info in the following thread is mixed up, at
least the poster in this particular post, notes that Windows shows
4GB available when "Memory Hole for PCI MMIO" is enabled. Note that
"joeWI" is using "Windows Server 2003 Enterprise Edition with
Service Pack 1" as his OS, and the experience with WinXP may not
be so straightforward.
http://www.bleedinedge.com/forum/showpost.php?p=78759&postcount=11
(thread)
http://www.bleedinedge.com/forum/showthread.php?p=78759
It is unclear to me, whether with, say, WinXP, you would need to
add /PAE or /3GB to the boot.ini file or not. When "memory hoisting"
is involved, to lift the memory in the memory mapped I/O hole, above
the 4GB mark, then more than 32bit addressing is needed. One way of
getting this is with PAE. Some of this is explained in this posting.
http://groups.google.ca/group/alt.msdos.batch.nt/msg/cac585f0671e2a2f?dmode=source&hl=en
If you do decide to go with 4x1GB, please post back your
experiences. I'm curious if Memtest86+ can handle this situation
or not. I'm also curious if there is any performance penalty,
over and above having to run command rate 2T at DDR400. To
figure that out, run a memory benchmark with two sticks, with
command rate 2T and memory set at DDR400. Then, insert the two
additional sticks and retest. Finally, enable the MMIO BIOS
setting and test again. Memtest86+ has a read bandwidth indicator
in its interface, and you can also use programs like Sisoft Sandra
and probably a few others, to benchmark the effects of these
options.
Don't expect four sticks of memory to run command rate 1T at DDR400.
I would not expect, even with Venice and San Diego versions of
processors, that this would be possible. Command rate 2T is used
to compensate for the memory loading of four sticks (32 loads on
the address/control signals).
Paul