Memory Speeds

[Freakfish1]

Can i use in a 680i 2 different speeds of RAM?

I have Samsung DDR2 667MHZ and Corsair XMS 800MHZ. Can i install 2 x GB of the corsair and 1gb of the Samsung?

 

[Will_3rd]

it can be done, but all the RAM will run at the speed of the slowest stick

 

[Yellowbeard]

It's also not advisable as you will be mixing 2 different types and possibly 2 different densities of ICs. This can in some cases cause instability or failure to boot. The only way to know for sure is to install and test.