Hey there, moudski.
You should have no trouble upgrading to 8GB of DDR3 memory, but from what I saw as compatible, it was 1600mhZ, although this shouldn't be an issue. I'd recommend that you contact the manufacturer's customer support and ask about that specifically, so that you are sure that the memory module you decide to get, will work flawlessly.
Hope that helps.
Boogieman_WD