ddr ram

[Guest]

I'm running vista ultimate with 2 x 512 mb of ram, system is going fine but
bit slow so added another 512 stick, system is running loads better but my
performance score on the memory has dropped from 4.5 to 3.7. how come??

 

[Michael]

Some motherboards require that memory be installed in pairs for optimum
performance. You would need to check your manual for actual specifications.
Michael

 

[Guest]

The speed of the RAM will default to that of the slowest stick. It seems the
RAM which you have added is not as fast as that which was already in your
computer. It's not a big deal really, the speed of the RAM is less important
than having enough RAM so you are now better off.

 

[Victek]

I'm running vista ultimate with 2 x 512 mb of ram, system is going fine

but
bit slow so added another 512 stick, system is running loads better but my
performance score on the memory has dropped from 4.5 to 3.7. how come??

Most likely the system switched from dual-channel mode (128 bit) to single
channel mode (64 bit) when you added the single stick. If you add another
512 meg stick (exactly the same as the first if possible) it should switch
back to dual channel mode and the performance index to go back up.

 

[Ken Blake, MVP]

The speed of the RAM will default to that of the slowest stick.

That's *not* correct. The so-called speed of the RAM is not really its
speed at all; it's its speed *rating*--the speed that it has been
tested to run reliably at. The speed that all the RAM runs at is set
by the motherboard.

So if you add faster RAM to existing RAM, it will all run at the old
speed, which happens to be the slower speed. But if you add slower
speed to existing RAM, it will all run at the faster speed--the
original speed--which may be too fast for the newer RAM, and may cause
failures.

 

[Michael Palumbo]

That's *not* correct. The so-called speed of the RAM is not really its
speed at all; it's its speed *rating*--the speed that it has been
tested to run reliably at. The speed that all the RAM runs at is set
by the motherboard.

So if you add faster RAM to existing RAM, it will all run at the old
speed, which happens to be the slower speed. But if you add slower
speed to existing RAM, it will all run at the faster speed--the
original speed--which may be too fast for the newer RAM, and may cause
failures.

Not quite . . .

If you have PC3200 (actually runs at 400MHz-200MHz 'double pumped') and add
a PC2700 stick (runs at 333MHz-166MHz 'double pumped') only a defective
motherboard will ignore the max speed rating of the slower stick. The
motherboard will slow the memory clock to match the speed of the lowest
rated stick in the system.

Case in point, I have a system running on an Intel 865GLC main board. I
originally had two 256 meg sticks running at 400 MHz, I acquired 2 256 meg
333 MHz sticks later and figuring that more slow ram is better than less
fast ram, popped them in and my system is now running the ram at 320 MHz
(the Intel board steps it down for stability reasons)

You can force most motherboards to run slower ram at a faster speed, but it
will not clock the ram any faster than the slowest stick when you use the
automatic settings.

All modern ram will basically 'report' to the motherboard the speed that it
was rated to run. The board will then adjust according to the lowest common
denominator.

In the 'old days' when you had to use jumpers (or manually in the BIOS
setup) to set the speed of the CPU, RAM, etc. this was true, (the RAM will
continue to run at the original speed regardless of the high and/or low
sticks mixed together) but computers are MUCH smarter about what's connected
to them these days.

Try it, get a slow stick and a fast stick, use only the fast stick, let the
system configure itself to the fast stick, then add the slow stick and see
what speed your RAM is set to after (do not use the manual settings for the
RAM clocks, leave them on AUTO.)

Mic

 

[Bruce Chambers]

I'm running vista ultimate with 2 x 512 mb of ram, system is going fine but
bit slow so added another 512 stick, system is running loads better but my
performance score on the memory has dropped from 4.5 to 3.7. how come??

Did you install a slower RAM module? Adding a slower module will force
the system bus to operate at the slower speed.

It is absolutely essential that any new RAM module(s) be fully
compatible with both the motherboard and/or any other RAM module(s)
already in the system. Additionally, there are sometimes jumper
switches on older motherboards that need to be reset for new RAM
configurations. Consult your motherboard's manual or the
manufacturer's web site for specific instructions and compatibility
requirements.

If you cannot lay your hands upon the computer's manual and the
manufacturer doesn't provide a support web site, you can use these
utilities to help determine the correct type of RAM needed:

SiSoft's Sandra
http://www.sisoftware.co.uk/index.php?dir=&location=sware_dl&lang=en

Belarc Advisor
http://www.belarc.com/free_download.html

Unlimited Possibilities' AIDA32
http://forum.aumha.org/overflow/aida32.zip

Also, Crucial Memory's web site (www.crucial.com) has a database
to help to find the right RAM for your specific make and model
computer and/or motherboard. (Incidentally, Crucial is the only company
from which I ever buy RAM. I've never been disappointed.)


--

Bruce Chambers

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