I'm ready to start my first PC build and I was hoping you guys could help me out. I purchased a Corsair XMS 8gb (1x8GB) memory for my Asus Sabertooth Z77 Motherboard (links below). It's not listed on the QVL, is there anyone with a similar or the same setup that can let me know if it will work?
If you put 2 or 4 cards, the memory will work in dual channel, meaning that 2 cards will be used at the same time(generally card in the 2nd and the 4th slot). So for a single process (eg. Firefox) the ram used in running the program will be divided among both the cards so to give you better speeds. There is about 50% to 70% speed gain.
For dual channel to work properly you need both the cards of the same specs(frequency, timings, voltages, even version). Similar cards do work in dual channel but can cause problems. Although in some motherboards you can set the timings individually for different memory channels.
If you can return your current ram card, do it and get two 4gB cards. Generally higher capacity cards are slower.
If you cannot return the card, go get another card right away, if you buy cards in the future they can cause problems. Since I've been the victim of a similar incident which caused my two hard drives to crash, I'd recommend you stand clear of this kind of problem.