I would just try it and see, I would imagine that your current o/c would need to tweaked to accomodate the extra stick of RAM though..
Also another thing to remember is, when running 4 sticks of RAM in these motherboards, in order to get it to run in triple channel mode, the 4th DIMM needs to be fitted in the first white slot nearest the CPU socket, or at least that's what the manual suggests, I haven't tried this personally.
TBH though, I can't see there being any benefits moving from 6GB to 8GB, well, there wouldn't be any benefits if you only use your PC for gaming.