My A7V333 jumps around like that depending on what I'm running. A CPU intensive program/game will cause it to vary up to 0.5 volts. On idle, it may only vary 0.1v.
However, I'm overclocking.. i'm not sure what the normal operation is for this board.
I'm afraid I don't have a straight answer to give, but it may shed some light on it.
- rp