I have a HP system which uses 2 * 1GB PC2-6400-666 RAM and want to buy another 2 GB.
I can't find any 666 timing RAM under Scan's DDR2 PC6400 (800Mhz) range, they all use 555 timing.. like this one: http://www.scan.co.uk/products/02gb-...d-cas-5-5-5-18
Will I run in to problems if I mix & match these 2 types of RAM with different timings in the same system?