I have 2 x 1GB on 800Mhz CL4 memory in my PC. I'm planning to upgrade to 6GB by adding a pair 2GB modules.
Is it ok if I buy CL5 modules or do I have to buy CL4?
What operating system are you using? You should be aware that you need to run a 64-Bit system to support more than 3,5GB of RAM.