A7V333 memory

  • Thread starter Thread starter Roy
  • Start date Start date
"Roy" said:
How many dimms can be in this Mobo and what dimms? (266 od 3x 333?)
grtz Roy
Click to expand...

You can get a manual here. e1010_a7v333.pdf is the main manual.
ie1010_a7v333.pdf is the specification change insert for the manual.

http://www.asus.com.tw/support/download/item.aspx?ModelName=A7V333&Type=All

From ie1010_a7v333:

"Three sockets are available for both 266MHz-PC2100 or 200MHz-PC1600
DDR DIMMs to form a memory size of 64MB to 3GB.

Only two (2) DIMMs will support 333MHz-PC2700;

if more than two 333MHz DIMMs are installed, the system automatically
reverts to a maximum speed of 266MHz."

What this means is, the bus speed is affected by the loading from
the DIMMs. Two double sided PC2700 will run at DDR333. If you attempt
to use three double sided modules, the memory bus will be set to
DDR266 by the BIOS. I don't know if the BIOS is clever enough to
recognize single sided DIMMs, as electrically, the bus should be
able to drive three single sided DIMMs at DDR333, but the BIOS will
probably still leave them at DDR266.

Your best choice is 2x512MB double sided PC2700 or PC3200 (as PC3200
will be slowed down by the BIOS to DDR333 anyway), inserted in
slot 1 and slot 3 DIMM slots.

From the Mushkin mainboard qualification page on A7V333:

"We found that running the memory bus asynchronous at 166 MHz with
the FSB does not overall increase system performance because of the
higher latencies and the buffers required for synchronization of
memory and FSB. Many of the boards exhibit some problems when DIMM
Slots 1 and 2 are populated simultaneously. Moving the DIMMs to
slots 1 and 3 usually solves these issues."

Mushkin had no notes on running 1GB double sided modules. If you do
decide to buy two of 1GB type modules, make sure they are not
"stacked" memories. A "stacked" DIMM has 32 memory chips instead of
the normal 16 memory chips on a double sided module. To get proper
modules, visit Kingston.com or Crucial.com, as they have 1GB modules
with only 16 chips.

So, that suggests if you are using a FSB266 processor, then
PC2100 CAS2 memory running at DDR266 will perform as well as
running at DDR333. When running FSB266/DDR333, extra memory
latches are used inside the Northbridge, and that is the
source of the extra latency (delay).

For performance estimates, see:
http://www.lostcircuits.com/motherboard/asus_a7v333/8.shtml

On a given graph, you should compare say 140 1:1 to 140 4:5,
as that is comparing synchronous operation to asynchronous
operation. The memory bandwidth improvement from a
FSB266/DDR333 type configuration is 8% using the Sandra
unbuffered benchmark.

HTH,
Paul
 
Paul said:
You can get a manual here. e1010_a7v333.pdf is the main manual.
ie1010_a7v333.pdf is the specification change insert for the manual.

http://www.asus.com.tw/support/download/item.aspx?ModelName=A7V333&Type=All

From ie1010_a7v333:

"Three sockets are available for both 266MHz-PC2100 or 200MHz-PC1600
DDR DIMMs to form a memory size of 64MB to 3GB.

Only two (2) DIMMs will support 333MHz-PC2700;

if more than two 333MHz DIMMs are installed, the system automatically
reverts to a maximum speed of 266MHz."

What this means is, the bus speed is affected by the loading from
the DIMMs. Two double sided PC2700 will run at DDR333. If you attempt
to use three double sided modules, the memory bus will be set to
DDR266 by the BIOS. I don't know if the BIOS is clever enough to
recognize single sided DIMMs, as electrically, the bus should be
able to drive three single sided DIMMs at DDR333, but the BIOS will
probably still leave them at DDR266.
Click to expand...

<quote>
Only two (2) DIMMs will support 333MHz-PC2700; if more than two 333MHz
DIMMs are installed, the system automatically reverts to a maximum speed
of 266MHz.
</quote>

That info you find in the "A7V333 Manual 1.01 Updates IE1010". The 1.01
manual release-date is March 2002 and the PDF-version of the "Updates"
was created 2002-03-28.
At that date the current BIOS was version 1005(2002-03-14), and there
have been ca 10-11 versions released since then.
¿Did the 2.x version(s) of the A7V333-board still come with the by then
old/outdated Manual+Updates from march 2002?
¿Does Asustek still claim the above anywhere else?, .. on their
Website(s)?

Anyways, there have been posters here [1-4] that have claimed that from
an unspecified BIOS version, possibly 1007, and onwards you can run the
memorybus at PC2700-speeds, (166MHz * DoubleDataRate -> 333MHz), even
with all 3 DIMM-slots filled.

N.B.: I have only 2 PC2700 DIMM-cards, so i haven't been able to verify
this personally.

References:
[1] 2002-07-28 - Big Easy <[email protected]>
Message-ID: <[email protected]>
I believe that was fixed in Bios 1007 or 1008 so you can use 3 sticks

[2] 2002-10-06 - Big Easy <[email protected]>
Message-ID: <[email protected]>
The 3 stick 333mhz Memory issue was fixed around Bios 1008 or there abouts

[3] 2002-10-07 - BGanger109 <[email protected]>
Message-ID: <[email protected]>
According to SEVERAL posters here - the 1008 bios FIXES this and it was
confirmed it was fixed.

[4] 2002-10-16 - to see several inputs see the 4 followups to the post:
Message-ID: <with the subject-name "A7V333 SDRAM Configuration?".
 
"... et al." said:
Paul said:
You can get a manual here. e1010_a7v333.pdf is the main manual.
ie1010_a7v333.pdf is the specification change insert for the manual.

http://www.asus.com.tw/support/download/item.aspx?ModelName=A7V333&Type=All

From ie1010_a7v333:

"Three sockets are available for both 266MHz-PC2100 or 200MHz-PC1600
DDR DIMMs to form a memory size of 64MB to 3GB.

Only two (2) DIMMs will support 333MHz-PC2700;

if more than two 333MHz DIMMs are installed, the system automatically
reverts to a maximum speed of 266MHz."

What this means is, the bus speed is affected by the loading from
the DIMMs. Two double sided PC2700 will run at DDR333. If you attempt
to use three double sided modules, the memory bus will be set to
DDR266 by the BIOS. I don't know if the BIOS is clever enough to
recognize single sided DIMMs, as electrically, the bus should be
able to drive three single sided DIMMs at DDR333, but the BIOS will
probably still leave them at DDR266.
Click to expand...

<quote>
Only two (2) DIMMs will support 333MHz-PC2700; if more than two 333MHz
DIMMs are installed, the system automatically reverts to a maximum speed
of 266MHz.
</quote>

That info you find in the "A7V333 Manual 1.01 Updates IE1010". The 1.01
manual release-date is March 2002 and the PDF-version of the "Updates"
was created 2002-03-28.
At that date the current BIOS was version 1005(2002-03-14), and there
have been ca 10-11 versions released since then.
¿Did the 2.x version(s) of the A7V333-board still come with the by then
old/outdated Manual+Updates from march 2002?
¿Does Asustek still claim the above anywhere else?, .. on their
Website(s)?

Anyways, there have been posters here [1-4] that have claimed that from
an unspecified BIOS version, possibly 1007, and onwards you can run the
memorybus at PC2700-speeds, (166MHz * DoubleDataRate -> 333MHz), even
with all 3 DIMM-slots filled.

N.B.: I have only 2 PC2700 DIMM-cards, so i haven't been able to verify
this personally.

References:
[1] 2002-07-28 - Big Easy <[email protected]>
Message-ID: <[email protected]>
I believe that was fixed in Bios 1007 or 1008 so you can use 3 sticks

[2] 2002-10-06 - Big Easy <[email protected]>
Message-ID: <[email protected]>
The 3 stick 333mhz Memory issue was fixed around Bios 1008 or there abouts

[3] 2002-10-07 - BGanger109 <[email protected]>
Message-ID: <[email protected]>
According to SEVERAL posters here - the 1008 bios FIXES this and it was
confirmed it was fixed.

[4] 2002-10-16 - to see several inputs see the 4 followups to the post:
Message-ID: <with the subject-name "A7V333 SDRAM Configuration?".
Click to expand...

The issue is not really the annoying feature of the BIOS protecting
you. The electrical performance of the bus is the issue, and this
population rule exists on a lot of single channel boards. If you
can manage to coax the board to run three double sided sticks at
DDR333, then go for it. But not everyone is going to be able to do
it. Install the third stick and test with memtest86. If you pass
error free, next step is boot into Windows and run Prime95 torture
test, to prove it is really stable.

The automatic setting of the memory clock to a DDR266 rate, was
put there to protect newbies. Most boards now, will let you shoot
yourself in the foot if you want, so the change to the BIOS is
more in line with the rest of the motherboards. (By removing the
automatic downclock, Asus is letting you experiment if you want.)

Conservative rules for single channel busses:

1 double sided at DDR400
2 double sided at DDR333
3 double sided at DDR266
(4 double sided at DDR200, if there was such a thing)

This is very similar to rules of thumb for PC100/PC133 memory.
And, as usual, some people will have done better than this.

3 double sided PC133
4 double sided PC100

You can sometimes substitute two single sided DIMMs for one of
the double sided DIMMs in the DDR rules above.

The rules will also change, if the single channel bus has
multiple address busses. The address bus and control signals
are the limiting factor on the bus, as all the chips on the
DIMMs are in parallel and feeding off the address at the same
time. The case of two double sided DIMMs is typically 32 chips
all feeding off one address bus. It is hard to design the bus
to handle both the light loading case (one single sided DIMM)
and the heavy loading case (three double sided DIMMs), as the
bus impedance changes drastically, and the motherboard uses
fixed resistor values to match the line. A multidrop bus is a
poor technical solution to the problem, and registered memory
is the perfect workaround, as each DIMM in that case has a buffer
chip to separate the 16 loads on the DIMM, from the motherboard.

As time has passed, there are some boards which have done better
than this. That is why I say, for the average person, the
conservative rules are there so they won't get stuck with an
extra DIMM in their hand that won't work for them. If you are
an experimenter, there is nothing preventing you from trying,
especially as you point out that the BIOS roadblock to doing
the experiment has been removed. But using three double sided
DIMMs will still be an experiment for you, with no certain
result.

HTH,
Paul
 
Paul said:
"... et al." said:
<quote>
Only two (2) DIMMs will support 333MHz-PC2700; if more than two 333MHz
DIMMs are installed, the system automatically reverts to a maximum speed
of 266MHz.
</quote>

Anyways, there have been posters here [1-4] that have claimed that from
an unspecified BIOS version, possibly 1007, and onwards you can run the
memorybus at PC2700-speeds, (166MHz * DoubleDataRate -> 333MHz), even
with all 3 DIMM-slots filled.
Click to expand...

The issue is not really the annoying feature of the BIOS protecting
you. The electrical performance of the bus is the issue, and this
population rule exists on a lot of single channel boards. If you
can manage to coax the board to run three double sided sticks at
DDR333, then go for it. But not everyone is going to be able to do
it. Install the third stick and test with memtest86. If you pass
error free, next step is boot into Windows and run Prime95 torture
test, to prove it is really stable.

The automatic setting of the memory clock to a DDR266 rate, was
put there to protect newbies. Most boards now, will let you shoot
yourself in the foot if you want, so the change to the BIOS is
more in line with the rest of the motherboards. (By removing the
automatic downclock, Asus is letting you experiment if you want.)
Click to expand...

< - explanation snipped ->

This would then also explain the one or two posters i've seen that
without explaining why, claimed it was a hardware issue that couldn't be
fixed with a BIOS upgrade.

Not a real "fix" in the BIOS then, more a change in the setting
possibilities.
HTH,
Paul
Click to expand...

Thanks, it sure did.
 
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