What memory do you have and in what configuration? I just had to replace my BIOS chip on my NF7-S R2 and when I first turned it on after reassembly I had the same thing. To fix the problem I had to rearrange the memory modules and put them into Slots 1 and 3. With memory in Slot 2 my system wouldn't POST and I got the same beep as you.
This was today by the way.