Your max RAM speed would be 400 (the rating of the RAM) if your BUS 
speed was 800 no matter if single or dual channel. My understanding of 
single versus dual channel is that dual channel provides alternate 
routes for memory use thereby giving a speed boast up to the maximum 
rating of the RAM but not exceeding 1/2 of the BUS speed. Think of a car 
operating uphill on a two lane (in each direction) highway with some 
trucks in one of the lanes. The car can operate faster than on a single 
lane (in each direction) uphill highway with some trucks in the only 
lane. But there is still a maximum speed limit.
 
However, I would have expected that your current RAM speed would 
indicate 266 (1/2 of 533). This question came up recently, but I don't 
remember if there was a technical explanation forthcoming from the 
members for a BUS speed of 533 and an indicated RAM speed of 333 instead 
of 266.

Tom Mayer

Peetie Wheatstraw wrote:
> 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?
>
>  Thanks,
>  Peetie
>
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