  We present an exploratory study of the thermodynamics of $N_f=3$ QCD with an
improved staggered fermions using the QCDOC supercomputer. We use a p4 action
with MILC-style smeared links (Fat 7). Some details of the implementation of
the p4 action on QCDOC are discussed and performance benchmarks are given. We
show preliminary results for the quark mass dependence of the pseudo-critical
temperature $T_c$ from several lattice volumes . We also make a comparison
between p4fat7 and the old p4 action.
