A8N-SLI Prem Memory Expansion Problem

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csm

I have a new ASUS A8N-SLI Premium MB with 1 gig (2x512MB 400MHz -
TWINX1024-3200C2PT) of Corsair XMS Platinum series DDR. The memory is
installed in the A-1 & B-1 slots. Everything works OK. However, when I add
a second gig of Corsair non-Platinum series (2x512MB 400MHz -
TWINX1024-3200C2) DDR memory to the A-2 and B-2 slots, the system will not
boot and the screen stays off. I have also paired the Platinum Series
memory to A-1 & A-2 and Non-Platinum series to B-1 & B-2 with no success.

Any ideas?

CM
 
csm said:
I have a new ASUS A8N-SLI Premium MB with 1 gig (2x512MB 400MHz -
TWINX1024-3200C2PT) of Corsair XMS Platinum series DDR. The memory is
installed in the A-1 & B-1 slots. Everything works OK. However, when I add
a second gig of Corsair non-Platinum series (2x512MB 400MHz -
TWINX1024-3200C2) DDR memory to the A-2 and B-2 slots, the system will not
boot and the screen stays off. I have also paired the Platinum Series
memory to A-1 & A-2 and Non-Platinum series to B-1 & B-2 with no success.

Any ideas?

CM
Click to expand...

This board (and I imagine *any* 939 board) is an absolute pain to work
with if you need lots of memory.

It doesn't like all four slots being filled; ASUS documentation
explicitly mentions you need single-sided memory in banks 3 and 4.

Even then, memory speed drops from 400 to 333; apparently this can be
forced back up to 400, but what effect it has on stability is anyone's
guess.

I'm forced to running this board with 2GB of memory, when I ideally need
a minimum of 4GB.


Odie
 
"csm" said:
I have a new ASUS A8N-SLI Premium MB with 1 gig (2x512MB 400MHz -
TWINX1024-3200C2PT) of Corsair XMS Platinum series DDR. The memory is
installed in the A-1 & B-1 slots. Everything works OK. However, when I add
a second gig of Corsair non-Platinum series (2x512MB 400MHz -
TWINX1024-3200C2) DDR memory to the A-2 and B-2 slots, the system will not
boot and the screen stays off. I have also paired the Platinum Series
memory to A-1 & A-2 and Non-Platinum series to B-1 & B-2 with no success.

Any ideas?

CM
Click to expand...

Try a pair of DIMMs in A1-B1 and check that the BIOS
reports dual channel and all (1GB) of memory is reported.

Repeat for A2-B2 slots.

The purpose of doing this, is to rule out a bad DIMM slot
or a bad chip select signal on the processor memory controller.

I've read a few posts now, where the Asus BIOS is using
a riduculous set of criterion for DIMM matching. I do seem
to remember reading somewhere, that they wanted four
identical DIMMs, but identical according to AMD, is to
match rows, columns, banks, and ranks. I think AMD also
wanted the same CAS for each DIMM, but I don't see that
as being a necessary requirement (previous motherboards have
survived quite nicely by selecting the slowest DIMM, to set
the timing on the controller). Document 26094 on the
AMD site contains all you could ever want to know about
"BIOS Writers guide" to the Athlon64 family, and Asus
doesn't seem to be doing exactly as the guide suggests.

It could be that this is one of those matching problems. Now,
in your case, if I go to the corsairmicro.com website, and
download datasheets for your two pairs of DIMMs, of course
they have the exact same specs. They are only supposed to
differ in the heat spreader on the module. However, you should
still get a copy of CPUZ from cpuid.com , and dump the
contents of each DIMM's SPD, and see to what extent the DIMMs
are the same. One DIMM will have a product name with the
word "Platinum" in it, which is a difference, but Asus should
not be comparing vendor strings on all four DIMMs for a
match.

In one case I read about, similar to your module choices,
the poster could not get the second set of DIMMs to be
seen by the BIOS. Only one pair would register and be
counted during the BIOS RAM test. Your symptoms are
a bit different than that, but it is the same issue, with
a crappy decision tree in the BIOS when dealing with
four DIMMs.

Other reauirements are, if operating at DDR333, then command
rate 1T timing should be OK. If operating at DDR400 with
your four DIMMs, then command rate 2T should work. DDR400 2T
is slightly faster than DDR333 1T. In one of the Anandtech
articles for the A8V Deluxe (an earlier board), they found -

"The A8V Deluxe is also very picky about the settings that
are used with 4 dimms in the 'Enable 2T' option in BIOS.
If an Auto setting is used with 4 dimms the board tries to set
1T and single channel memory at a lower memory speed. If 'Auto'
is selected and memory timings are forced to DDR400 the board
would not boot. With 4 dimms, you will need to set the 2T
option to 'Enable 2T' for proper Dual-Channel operation
at DDR400."

Perhaps your BIOS has the same bug ? Try setting the Enable 2T
option so the BIOS has no choice but to use 2T timings, before
installing the second set of sticks. Maybe that will coax some
life from it.

Paul
 
FOLLOWUP: I purchased an identical 1 gig (2x512MB 400MHz -
TWINX1024-3200C2PT) of Corsair XMS Platinum series DDR memory to match the
previous gig. Same problem. All 4 slots filled with identical DDR memory.
I don't think this Corsair works in 4 strip configuration. I'm going to
take the extra gig back and look for 2 strips of 1 gig each to get to 2
gigs. I'm going to give up on the 4 strip configuration.

ASUS A8N-SLI Premium MB - v1005 BIOS
AMD Athlon 64 3800+
1 Gig Corsair Platinum Series (2x512MB 400MHz - TWINX1024-3200C2PT)
1 Maxtor SATA 250 16meg cache 7200RPM HD
2 Maxtor SATA 120 8meg cache 7200RPM HD (Raid-Striped)
BFG nVidia 6800GT PCIe

CM
 
"csm" said:
FOLLOWUP: I purchased an identical 1 gig (2x512MB 400MHz -
TWINX1024-3200C2PT) of Corsair XMS Platinum series DDR memory to match the
previous gig. Same problem. All 4 slots filled with identical DDR memory.
I don't think this Corsair works in 4 strip configuration. I'm going to
take the extra gig back and look for 2 strips of 1 gig each to get to 2
gigs. I'm going to give up on the 4 strip configuration.

ASUS A8N-SLI Premium MB - v1005 BIOS
AMD Athlon 64 3800+
1 Gig Corsair Platinum Series (2x512MB 400MHz - TWINX1024-3200C2PT)
1 Maxtor SATA 250 16meg cache 7200RPM HD
2 Maxtor SATA 120 8meg cache 7200RPM HD (Raid-Striped)
BFG nVidia 6800GT PCIe

CM
Click to expand...

Did you try setting "Enable 2T" command rate, before installing
the second pair ? Crank the memory clock down to DDR333, and see
if that is enough. I want to be able to distinguish between a
matching failure problem, versus using too aggressive a setting
for the memory clock or the command rate.

Also, with your two sets of Platinum, compare their SPD contents
with CPUZ from www.cpuid.com . Perhaps there is still a difference
between them.

Paul
 
Paul,

I'll try that next. However, I did try it with 3 strips installed. The
system booted in single mode with 1.5 gigs of ram. Either strip worked in
either of the remaining slots (A2 & B2). There is a lot of talk on the ASUS
site. Appears to be an ongoing problem.

CM
 
"csm" said:
Paul,

I'll try that next. However, I did try it with 3 strips installed. The
system booted in single mode with 1.5 gigs of ram. Either strip worked in
either of the remaining slots (A2 & B2). There is a lot of talk on the ASUS
site. Appears to be an ongoing problem.

CM
Click to expand...

That means you have a Rev.E processor. According to the 26094 AMD
document, Rev.E processors now have the ability to use all slots
in single channel (64 bit) memory mode. That is why three sticks
worked and all the memory (1.5GB) was detected. If you had a
release of processor previous to Rev.E, either the computer
wouldn't POST in that config, or some of the memory would not
be detected.

*****
Previous to Rev.E

1 stick (use B1 or B2, as Ax slots won't work)
2 sticks (B1 & B2 - single channel, A1 & B1 - dual channel,
A2 & B2 - dual channel)
4 sticks (pair in A1 & B1, pair in A2 & B2, less hassle if all
DIMMs identical, unclear what rules the BIOS is using)

*****
Rev.E

1,2,3, or 4 sticks now possible.
Sticks can now be placed in the Ax slots, whereas before
Ax slots were only to be used for dual channel configurations.
B is no longer the "primary bus", A and B bus are equals.

Combinations which are not paired, revert to single channel
64 bit mode. If your DIMMs are not matched to the BIOSes
satisfaction, it will throw the board into single channel
mode. 2 unmatched sticks, 4 unmatched sticks, and any kind
of 3 sticks, can give single channel mode.
*****

It sounds like the BIOS decision tree is a mess. Maybe
they should get their "A+" BIOS team working on this,
instead of their "maintainer" team. (The maintainer team
are those guys who make broken BIOS releases at release
levels like 1021 :-)

I guess what we need to find now, is someone who got four
sticks to work. And then ask them why it works...

Paul
 
Thanks for all the great help and ideas. I took back the TWINX1024 strips,
shelled out the extra money and purchased the TWINX2048 and its up and
running with 2 gigs of ram in the dual chan mode. It will be interesting to
see what, if anything, ASUS does.

Great Group!
CM
 
I'm sure this is a stupid question but -

How do I tell if my A8v deluxe is running in dual channel mode - does the
bios report this during the boot phase like the Giabyte boards?

CPU-Z reports that the memory channels are dual and that the frequency is
166.7 - does this mean dual channel at 333 mhz?

I have corsair double sided ram - get the same result with 1 stick in A1 and
1 in B1 as I do with all slots filled.

thanks in advance.
 
Peter Seymour said:
I'm sure this is a stupid question but -

How do I tell if my A8v deluxe is running in dual channel mode - does the
bios report this during the boot phase like the Giabyte boards?

CPU-Z reports that the memory channels are dual and that the frequency is
166.7 - does this mean dual channel at 333 mhz?

I have corsair double sided ram - get the same result with 1 stick in A1
and 1 in B1 as I do with all slots filled.

thanks in advance.
Click to expand...

The A8N bios will indicate whether memory is in dual channel mode (disable
the fast boot so you can see it easier before it rolls off the screen).
Don't know about the A8V bios.
 
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