  We present the results of a search for neutrino point sources using the
IceCube data collected between April 2008 and May 2011 with three partially
completed configurations of the detector: the 40-, 59- and 79-string
configurations. The live-time of this data set are 1,040 days. An unbinned
maximum likelihood ratio test was used to search for an excess of neutrinos
above the atmospheric background at any given direction in the sky. By adding
two more years of data with improved event selection and reconstruction
techniques, the sensitivity was improved by a factor 3.5 or more with respect
to the previously published results obtained with the 40-string configuration
of IceCube. We performed an all-sky survey and a dedicated search using a
catalog of \textit{a priori} selected objects observed by other telescopes. In
both searches, the data are compatible with the background-only hypothesis. In
the absence of evidence for a signal, we set upper limits on the flux of muon
neutrinos. For an E$^{-2}$ neutrino spectrum, the observed limits are between
0.9 and $23.2\times 10^{-12}$ TeV$^{-1}$ cm$^{-2}$s$^{-1}$. We also report
upper limits for neutrino emission from groups of sources which were selected
according to theoretical models or observational parameters and analysed with a
stacking approach.
