using dual ddr 400 with a 533mhz cpu

[kaizersose]

i have the new abit ic7 mobo but dont want to drop the cash on on a P4c just yet. if i buy a P4b meant for a 533 mhz bus, does that negate any advantages provided by a dual ddr setup? thanks for the help, a bit new at this.

 

[snidy1]

It'll work, but the memory won't run at 400 speeds unless you have 800 FSB.

 

[AgaBoogaBoo]

That'll give you a lot more overclocking headroom for now, but you can also downclock the ram to 266mhz each since you have dual channel ram and set the CAS latency to 2. That would give better performance since it would be on a 1:1 ratio.

 

[Viper96720]

Use the dividers and run your fsb at 133Mhz. Set NB Strap to 800 then use the 3:2 divider so your memory is about 200Mhz.
May want to read this also memory timing issues

 

[Lord Evermore]

Intel chipsets don't allow memory to run at just any speed. With a 533MHz bus setting, the memory can only be set to run at 266MHz and 333MHz (surprising that they allow dual-333 operation since dual-266 provides enough bandwidth). In single channel mode, it's also limited to 333MHz. You can only use 400MHz if you set the fsb to 800MHz.

There's pretty much no performance gain from setting dual-channel memory to more than half the speed of the frontside bus, since the two channels combine to provide the amount of bandwidth the CPU needs, and any extra is mostly wasted.