  In this paper we present high time-resolution observations of GW Librae and
SDSS J161033.64-010223.3 -- two cataclysmic variables which have shown periodic
variations attributed to non-radial pulsations of the white dwarf. We observed
both these systems in their quiescent states and detect the strong pulsations
modes reported by previous authors. The identification of further periodicities
in GW Lib is limited by the accretion-driven flickering of the source, but in
the case of SDSS 1610 we identify several additional low-amplitude
periodicities. In the case of SDSS 1610, there is evidence to suggest that the
two primary signals have a different colour dependence, suggesting that they
may be different spherical harmonic modes. We additionally observed GW Lib
during several epochs following its 2007 dwarf nova outburst: the first time a
dwarf nova containing a pulsating white dwarf has been observed in such a
state. We do not observe any periodicities, suggesting that the heating of the
white dwarf had either switched-off the pulsations entirely, or reduced their
relative amplitude in flux to the point where they are undetectable. Further
observations eleven months after the outburst still do not show the pulsation
modes previously observed, but do show the emergence of two new periodic
signals. In addition to the WD pulsations, our observations of GW Lib in
quiescence show a larger-amplitude modulation in luminosity with a period of
approximately 2.1 hours. This has been previously observed, and its origin is
unclear: it is unrelated to the orbital period. We find this modulation to vary
over the course of our observations in phase and/or period. Our data support
the conclusion that this is an accretion-related phenomenon which originates in
the accretion disc.
