Every power supply has a small amount of ripples as there is standard range that a power supply should be within. In one test (the only I've personally seen) by johny guru (I think) it showed that the gamerxtreme is outside those limitations.
The ATX & EPS guideline tolerance for the +12V rails is 120mV p-p. To my knowledge, the ripple from the OCZ GXS is well within those boundaries, therefore, there is no need for concern. My bro has been using one for about 6 months (O/C'd E6600, 8800gtx 768mb, 2gb ram), and it hasn't blown up on him!