mixing ddr2 modules

I have EP45-UD3L mobo with two identical ddr2 modules installed. Can I
add two more modules of the same size but different brand to make thme
work dualchannel ?

Aaron Leecher wrote:
I have EP45-UD3L mobo with two identical ddr2 modules installed. Can I
add two more modules of the same size but different brand to make thme
work dualchannel ?

You can do something like this. The manual will tell you which slots
are "across" from one another. I put the slot numbers in brackets ().

Channel 0 Channel 1

(1) Samsung 1GB (3) Samsung 1GB

(2) Micron 1GB (4) Micron 1GB

That would be a conventional dual channel setup, suitable for just
about any motherboard.

Your P45 also supports Flex memory. That allows a configuration like this,
where you can purchase one additional module, and it still runs Dual Channel.

Channel 0 Channel 1

(1) Samsung 1GB (3) Micron 2GB

(2) Samsung 1GB (4) ---

The reason that works, is Intel Flex Memory only requires that the total
quantity of memory on each side matches. In the example, the two Samsung
modules give a total of 2GB on Channel 0, matching the total quantity
of memory provided by the single Micron 2GB module. So in fact, your
motherboard, with P45, supports a more relaxed mode of Dual Channel
operation.

You can use either setup, if you want.

Another consideration, might be the voltage operating range of the
modules, or whether all the modules are the same speed or not. It
might require some testing and tuning, if the modules are radically
different from one another. For example, say one pair of modules
with a maximum voltage of 2.0V are paired with modules having 2.4V
maximum voltage. Since you're limited to one voltage supply, then
the VDimm setting you use, would have to be suitable for the 2.0V module
(to stay within the usage limits, for warranty purposes). You would
have to then test, using memtest86+ and the like, to figure out what
is the best setting for all the RAM.

If you purchased all matching modules, that may make it slightly
easier to predict what to expect. In the testing that Anandtech used
to do, there wasn't much timing penalty for 2 modules versus 4 modules,
so there shouldn't be much trouble dialing in the set of matched 4 modules.
But if you mix really different kinds of modules, you may not be
very happy with the results.

If I currently owned 2x1GB modules, and I had your motherboard, then
I would probably buy another 2x1GB modules. I would not particularly
try to use the Flex memory option. The reason I say that, is a lot
of people use Enthusiast grade memory for such upgrades, and it may be
harder to find the ideal operating conditions for the three modules.
The more matched the modules are, potentially the easier it will be
to tune them.

To learn more about your P45, try PDF page 527 here. This is where
I check what modes a chipset supports. This is the datasheet for
the P45 chip. (Basically this says you have true dual channel mode,
dual channel with Flex mode, single channel with Flex turned off.)

http://www.intel.com/Assets/PDF/datasheet/319970.pdf

Paul

Thank you Paul for your help, you answered all my questions.


On 4/9/2010 4:12 PM, Paul wrote:
Aaron Leecher wrote:
I have EP45-UD3L mobo with two identical ddr2 modules installed. Can I
add two more modules of the same size but different brand to make thme
work dualchannel ?

You can do something like this. The manual will tell you which slots
are "across" from one another. I put the slot numbers in brackets ().

Channel 0 Channel 1

(1) Samsung 1GB (3) Samsung 1GB

(2) Micron 1GB (4) Micron 1GB

That would be a conventional dual channel setup, suitable for just
about any motherboard.

Your P45 also supports Flex memory. That allows a configuration like this,
where you can purchase one additional module, and it still runs Dual
Channel.

Channel 0 Channel 1

(1) Samsung 1GB (3) Micron 2GB

(2) Samsung 1GB (4) ---

The reason that works, is Intel Flex Memory only requires that the total
quantity of memory on each side matches. In the example, the two Samsung
modules give a total of 2GB on Channel 0, matching the total quantity
of memory provided by the single Micron 2GB module. So in fact, your
motherboard, with P45, supports a more relaxed mode of Dual Channel
operation.

You can use either setup, if you want.

Another consideration, might be the voltage operating range of the
modules, or whether all the modules are the same speed or not. It
might require some testing and tuning, if the modules are radically
different from one another. For example, say one pair of modules
with a maximum voltage of 2.0V are paired with modules having 2.4V
maximum voltage. Since you're limited to one voltage supply, then
the VDimm setting you use, would have to be suitable for the 2.0V module
(to stay within the usage limits, for warranty purposes). You would
have to then test, using memtest86+ and the like, to figure out what
is the best setting for all the RAM.

If you purchased all matching modules, that may make it slightly
easier to predict what to expect. In the testing that Anandtech used
to do, there wasn't much timing penalty for 2 modules versus 4 modules,
so there shouldn't be much trouble dialing in the set of matched 4 modules.
But if you mix really different kinds of modules, you may not be
very happy with the results.

If I currently owned 2x1GB modules, and I had your motherboard, then
I would probably buy another 2x1GB modules. I would not particularly
try to use the Flex memory option. The reason I say that, is a lot
of people use Enthusiast grade memory for such upgrades, and it may be
harder to find the ideal operating conditions for the three modules.
The more matched the modules are, potentially the easier it will be
to tune them.

To learn more about your P45, try PDF page 527 here. This is where
I check what modes a chipset supports. This is the datasheet for
the P45 chip. (Basically this says you have true dual channel mode,
dual channel with Flex mode, single channel with Flex turned off.)

http://www.intel.com/Assets/PDF/datasheet/319970.pdf

Paul