What speed does DDR-SDRAM memory work in 800 Mhz FSB system

[vsenapati]

I have a Intel D875PBZ Mainboard which has 800 Mhz FSB. I have two memory sticks of each 256 MB PC3200( 400 Mhz ). Does the data transmission between the memory sticks and Processor via the mainboard take place at 400 Mhz or 800 Mhz ? If, the speed is only limited to 400 Mhz(which I strongly suspect) then what is the advantage of going for an expensive mainboard such as D875 PBZ ? I could have stuck to a D845 GL mainboard which is much less priced.

[pixel]

The advantage of going for an expensive motherbaord (which has dual-channel memory capabilities) means you can run a HT pentium 4 at its full FSB capacity.

Your motherboard (with an 875 chipset) will run memroy in a dual-channel mode, meaning you can run it at 800MHz. (a motherboard with 865 chipset also has dual-channel capabilities).

The other one you mentioned (with an 845 chipset) does not have capabilities of dual-channel memory, meaning you can only run a pentium 4 with 533MHz FSB.

The way it works is it uses the 2 same specifications sticks of ram (in your case 2x256MB of 400MHz ram). The motherboard then uses its dual-channel function and runs the two sticks simultaneously, giving you 2x400Mhz which means 800MHz of bandwidth, the same as a pentium 4 with HT.

Of course, if you only plan on running a celeron on it or a 400MHz or 533MHz pentium 4, you would have been cheaper off with the 845 chipset motherboard.