I wanted to put more memory in on my board since I finally got my GTX560 Ti working after installing the latest driver. I currently have 4 GB OCZ SLI-Ready DDR2 2 x 2 GB in my system. I am kind of strapped for cash right now and wanted to put in G.SKILL 4GB (2 x 2GB) 240-Pin DDR2 SDRAM DDR2 800 (PC2 6400). they are both 800 and was wondering if there is a problem with mixing RAM as I never had to do that before. I'm trying to get the best out of my rig to play bf3
More aboutmixing memory
Most of the time it works if you have ram with the same voltage, it can though not be guarantied to be trouble free.
Generally it can work, but not guaranteed by any means.