Adding memory lowered performance rating

[Guest]

Can anyone explain this to me?

I just added 50% more memory to my system. I went from 2GB of DDR400
(PC3200) memory to 3GB of DDR400, and the performance index for memory went
from 4.9, down to 4.5. I found some information on the Microsoft Knowledge
database which suggested deleting all of the old performance index readings,
did that, but still ended up with a 4.5 score.

Is this normal? I would have thought adding MORE memory would increase my
score. I'm using Vista Home Premium with an Athlon 64 X2 4200+ CPU. I
originally had 2 1GB sticks of memory,and added 2 more 512MB sticks, keeping
everything paired up nicely.

HELP! (pretty please?)

 

[Spirit]

Maybe you added slower memory.

 

[Peter Lawton]

I expect your memory might now be running slower unfortunately, due to a
limitation of the AMD memory controller.

The Athlon 64 has a dual channel memory controller that can run 4 single
sided DIMMs or 2 double sided DIMMS at 400MHz, but can't run 4 double sided
DIMMs at more than 333MHz.

Run something like CPUz to tell you the speed your memory's actuelly working
at http://www.cpuid.com/cpuz.php

As 1GB single sided DIMMs are almost unnobtainable yours are probably double
sided, so you could run just that pair at 400MHz (provided they're placed
one on each controller) but when you added the extra DIMMs, either single or
double sided, the memory controller can'e run them at more than 333MHz.

Basically when you're using double sided DIMMs the only way to run them at
400MHz is to have them one on each memory controller and have the second
slot on that controller empty, because each controller can only run 2
"sides" of memory at full speed, any more and it drops the speed down.

Peter Lawton

 

[Guest]

Thank you for the information. It does indeed seem to answer the "why".

One follow-up question though, if you'd be so kind....assuming you are
correct (which I have no reason to doubt), does my system actually have more
capability running with 2GB of DDR400, running at 400MHz, or with 3GB running
at 333MHz? On the one hand, I have less memory, which is running faster. On
the other hand, I have 50% more memory, but running slower.

Thanks!

 

[Guest]

Your system would be faster with the higher clocked RAM. Although with 3GB
your system has more RAM to work with. So both would have their benefits,
you would need to decide depending on your usage.

The better choice is open to personal interpretation. In my opinion, I
would choose to have 2GB running at the higher clock speed. Providing 2GB is
enough for each of the programs you use then this is the better choice.

However, if you use programs which like to have more RAM, video editing, 3d
or graphic design, then you would be better to have more RAM. In this case
then the 3GB at DDR333 would serve you better.

As long as you have *enough* RAM then more is not better. So it is not a
clear cut choice, you will have to decide depending on your computer usage.