Hi all,

I'll do a short post and then flesh it out as and if anyone needs more info.

System

CPU = Athlon 2700
Motherboard = MSI K7N2G ( Nforce 2 / AGPx8 )
Graphicscard = XFX FX5900XT 128meg
Windows XP SP2

I was running two 512meg DDR333 ram modules, cheapest I could get and two different companies.

I have just replaced them with two 1 gig DDR 400 modules by Geil.

All my benchmarks have gone down
I have been messing about in BIOS etc but with no luck - any ideas or pointers would be most welcome.

Thanks in advance,
Sean.

how much are you talking about and what are your timings for each?

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does that motherboard support dual channel? maybe the 2x1gb geils aren't running in dc.
were your 512x2 ddr333 running in dc?

You get better performance from 2x512MB vs. 2x1GB.

The reason is because for normal desktop use 1GB is optimal under WIN XP.

Since your computer has to provide the memory-mapping/page-filing for the entire memory space (1GB or 2GB in your case), and since you don't normally use more than 1GB memory, the extra unused memory is equivalent to a loss in performance.

Performance is measured in terms of execution time. Think about it this way.. you are looking for a name in a phone book. The phone book is mapped alphabetically for you already. Perhaps you perform a binary search through the book by starting in the middle, and dividing your search in half by every flip left or right of the current page.

Say your book is twice as big, it doesnt take you twice as long, but it does take you longer. Computers are binary machines, and so this analogy is the same concept for computers.

Also, if you have a large city, you need a large phone book. If you have a small city, you need a small phone book. It doesnt make sence to have a large phone book for a small city.

Just like you want to match the size of the city with the size of the phone book, you also want to match your memory usage with the memory size (maybe a few more pages/megabytes to make up for surges in population/data)

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RichPLS.

Benchmarks and scores are as follows

2001 333= 13,823 400= 13,813
2003 333= 5,186 400= 5,170
X2 333= 75.512 400= 75,373

danizaken.

Yes the Mobo supports DC and I have the modules in the correct slots.

Brent.

I understand what your saying but I would still have expected a speed boost due to the increase in DDR speed.
Also, by your reckoning, using just one of the modules would be faster than using two but this isn't the case I'm affraid. With one 1Gig module the scores fall even lower again though not by much.

Thanks again for the replys guys. My Dad has a slightly newer Mobo than me and I'm going to try the modules in his set-up next time I visit him.

I wouldn't expect DDR400 to be faster than DDR333 on a system with a DDR333 CPU bus. Also, the chances are the DDR400 defaults to slower CAS values.

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Arggg is that the problem ? - I am capable enough to know that the Mobo accepts DDR400 ( basicaly I can read the box ) but CPU bus is getting into the technical stuff for me

Thanks for the reply.

Yes, you would see a performance boost using 512MB rather than 1GB if in reality you are using 512MB (or just under) of system memory.

____________________________________________________
"Memory with lifetime warranty? So, whose lifetime is that?"
<A HREF="http://www.brentcrowley.com/" target="_new">homepage</A>
AIM BrentUnitedMem

But not nearly as much of a loss as if your CAS timing settings are increased.

2 gigs at CAS 2 are faster than 1-gig at CAS 3

<pre><font color=red>°¤o,¸¸¸,o¤°`°¤o \\// o¤°`°¤o,¸¸¸,o¤°
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So I got me a pen and paper And I made up my own little sign</pre><p></font color=red>

I would have to assume the comparison is just between memory sizes at the same latency.

..of course

____________________________________________________
"Memory with lifetime warranty? So, whose lifetime is that?"
<A HREF="http://www.brentcrowley.com/" target="_new">homepage</A>
AIM BrentUnitedMem

So according to what Master Crashman is saying, the memory is limited by the CPU (There is a latency differece between DDR-400 and DDR-333)

If both modules are being run at the same speed, as limited by the CPU, AND you are running the same setup on both 2x512MB and 2x1GB modules, you would expect to see a performance decrease by the addition of the unused memory.


____________________________________________________
"Memory with lifetime warranty? So, whose lifetime is that?"
<A HREF="http://www.brentcrowley.com/" target="_new">homepage</A>
AIM BrentUnitedMem

Also, asynchronous clocks can lead to slightly decreased system performance due to the memory controller doing more work.

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<font color=red>Only a place as big as the internet could be home to an ego as large as Crashman's!</font color=red>

Your memory can only transfer data as fast as it gets it. The CPU bus for the XP2700+ is DDR333 (166MHz clock using DDR technology), so DDR400 memory can't get that data any faster than the CPU bus can transmit it.

Furthermore, it's sometimes possible to get better performance from DDR400 by lowering the speed to DDR333, when using a CPU with a "333MHz" bus. The reason is, the memory controller has to do the work of synchronizing data between the two different bus speeds.

<font color=blue>Only a place as big as the internet could be home to a hero as big as Crashman!</font color=blue>
<font color=red>Only a place as big as the internet could be home to an ego as large as Crashman's!</font color=red>

I get it now, thanks

Looks like it's time to go 64 bit I suppose !