mgb_

I have two machines with 4GB (2x2GB) of RAM in each, they are different brands but look to be the same spec. I need to upgrade to 8GB in one of the machines and it wouldn't hurt to upgrade the other. I noticed for almost the same price I can get 2 x 4GB of another brand for the price of 2 x 2GB of the two I already own. So, here are the questions: Can I combine the two different brands i already have (2 Corsair x 2 Kingston x 2GB) into one system? If I can combine them would it make a difference as to what system I put the unmatched pair into? (The two systems and their uses are below) If I can't combine them what are the drawbacks, if any, of having the same brand but different size sticks? Like 2 x 2GB and 2 x 4GB sticks bringing the total to 10GB or or maybe 2 x 2GB and one 4GB to bring it to 8GB if thats better for some reason? System 1: HTPC running Win7, GIGABYTE GA-H67MA-UD2H-B3 motherboard. system 2: Media/File server running unRAID, MSI 880GMA-E53 motherboard. Memory 1: CORSAIR XMS3 4GB (2 x 2GB) 240-Pin DDR3 SDRAM DDR3 1600 (PC3 12800) Desktop Memory Model CMX4GX3M2A1600C9 Specifications: http://www.corsair.com/us/cmx4gx3m2a1600c9.html New Egg Link: http://www.newegg.com/Product/Product.aspx?Item=N82E16820145260 Memory 2: Kingston HyperX Blu 4GB (2 x 2GB) 240-Pin DDR3 SDRAM DDR3 1600 (PC3 12800) Desktop Memory Model KHX1600C9D3B1K2/4GX Specifications: http://www.kingston.com/datasheets/KHX1600C9D3B1K2_8GX.pdf New Egg Link: http://www.newegg.com/Product/Product.aspx?Item=N82E16820104203