  In a dwarf nova, the accretion disk around the white dwarf is a source of
ultraviolet, optical, and infrared photons, but is never hot enough to emit
X-rays. Observed X-rays instead originate from the boundary layer between the
disk and the white dwarf. As the disk switches between quiescence and outburst
states, the 2-10 keV X-ray flux is usually seen to be anti-correlated with the
optical brightness. Here we present RXTE monitoring observations of two dwarf
novae, VW Hyi and WW Cet, confirming the optical/X-ray anti-correlation in
these two systems. However, we do not detect any episodes of increased hard
X-ray flux on the rise (out of two possible chances for WW Cet) or the decline
(two for WW Cet and one for VW Hyi) from outburst, attributes that are clearly
established in SS Cyg. The addition of these data to the existing literature
establishes the fact that the behavior of SS Cyg is the exception, rather than
the archetype as is often assumed. We speculate on the origin of the diversity
of behaviors exhibited by dwarf novae, focusing on the role played by the white
dwarf mass.
