Up to 650kHz high repetition active Q-switching was achieved with a pulse-width of <40ns by using a diode-side-pumped Nd:Gd(x)Y(1-x)VO(4) bounce amplifier. An average output power of 17.5W was obtained at a pump power of 41W. The pulse repetition frequency range of the stable Q-switching operation was adjusted without any loss of the average output power by changing the Gd:Y mixture ratio.