Conroe FSB is 1066 / XPS has memory running at 667

I'll give it a try.

CPU and memory speeds are both derived from the system bus speed.  CPU and memory speeds are closely related.  Together they determine your system bandwidth (data transfer capability).  More bandwidth is good, especially for system performance in gaming and other intensive applications.  It is also important that neither the CPU nor the RAM acts as a bottleneck on the other.

To look at the numbers, the system bus for a Core 2 CPU is the FSB divided by four because data is transferred four times per clock cycle ("quad pumping").  That means a 1066 FSB equals a 266mhz system bus for the CPU.   Double data rate (or "DDR") memory has an effective bandwidth of two times the system bus so DDR667 has a system bus of 333Mhz.

DDR667 is really the minimum memory you should use with a 1066 Core 2 processor. You could get by with DDR533 (two times the CPU system bus) (and remember, dual channel memory is installed in paired sticks, increasing the effective memory bandwidth), but it is good to have a little extra room in the memory to handle other system elements (the PCI-E, etc.)

To overclock the system you would want to have DDR800 capable memory, so that you have room to increase the system bus on both the CPU and the memory and thereby increase your system's bandwidth.

FYI, the clock speed of a CPU is the product of the bus speed (266 in this example) times a specified clock multiplier.  Changing either element, the system bus or the mulitplier, results in a higher CPU clock speed.  But assuming an equal total clock speed, you will generally gain more performance improvement in gaming with a high bus speed and a lower multiplier than vice versa.

Other important issues in terms of performance include memory timings.  If you really get interested in this subject I recommend the enthusiast forum at www.hardocp.com.

Message Edited by Aivas47a on 08-04-200602:21 PM

Message Edited by Aivas47a on 08-04-200602:56 PM

Message Edited by Aivas47a on 08-06-200611:59 AM