Hello... if you you are planning on using both pairs of 553 and 667... your Ram speed is still limited to the slowest Ram speed installed... making the 533 Ram run at 667 could cause you problems in time.
Go into the BIO's and find the option to change Ram speed and re-boot.
The spec sheet only says "Intel (Big Lake) 945G Motherboard", but I will check out the site you posted when I get home.
I am going to upgrade the other two RAM so I will wait until they are installed before switching the speed to keep it consistent.
Hello... PLEASE!!!! don't invest alot of your time and $$$ into getting that RAM speed upgrade or compatability... You will not notice it at all... What is important is the amount of ram you add to your SYSTEM. You could use DDR2 800... it is backward compatable.