The numbers, 533 MHz system bus speed and 333 MHz memory bus speed, actually 
are sometimes referred to as "effective" bus speeds, as in "the system bus 
is effectively running at 533 MHz".  The actual bus speed in clock ticks is 
only 133 MHz for the system bus and the 166 MHz for the memory bus.  The 
higher numbers are arrived at by taking into account that the Pentium 4 
motherboard's front side bus is capable of handling four bits of data per 
clock cycle (i.e., it is "quad-pumped", in Intel's lingo) and the Double 
Data Rate memory is capable of handling 2 bits of data per cycle (thus, the 
double data rate).  4 x 133 = 533, and 2 x 166 = 333.

A utility like CPU-Z (http://www.cpuid.com/cpuz.php) will break these things 
down for you when it reports on what your motherboard, memory, and processor 
are doing.

I don't know what options your motherboard offers in its BIOS, but you may 
be able to increase the memory bus speed to 200 MHz (400 MHz, effective), 
since you memory should support this speed.  I don't know if being able to 
do so would result in any tangible overall performance gain or not.  I guess 
you'd have to try it and test it out.

Different BIOS represent the bus speeds in different ways.  They may show 
them as a ratio of one to the other.  For example, you currently are running 
4/5 ratio of system/memory bus speeds.  Increasing your memory to 200 MHz 
should result in a 2/3 ratio (133/200).

John Sproule


----- Original Message ----- 
From: "Peetie Wheatstraw" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Thursday, July 13, 2006 9:15 AM
Subject: [PCBUILD] DDR Memory speed of new build


> Greetings,
>
> I recently acquired (from TigerDirect) and assembled:
>
>  Intel Desktop Board D865GVHZ
>  Celeron D 345 cpu (max 533 mhz fsb)
>  Ultra 512MB PC3200 DDR 400MHz CL3 Memory (#30215)
>
> With 1 stick of memory, the Intel AMI bios etc reported:
>
>  System Bus Speed      533
>  System Memory Speed   333
>  Single Channel
>
> After adding a 2nd stick of (#30215) memory, the bios etc reported:
>
>  System Bus Speed      533
>  System Memory Speed   333
>  Dual Channel
>
> The "System Bus Speed" is obviously the max speed
> supported by the installed cpu. My Celeron D 345 cpu
> supports a max 533 mhz fsb (Dual Channel).
>
> It is my impression that my "System Memory Speed" should be
> at 533 mhz with Dual Channel, if my memory is downward
> compatable (and capable of running at 266 mhz in each of 2
> channels)?
>
> Intel Active Monitor also indicates memory speed is DDR333.
>
> Can anybody make sense of the DDR333 memory speed in this
> context?

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