The computational biology community is pretty heavily into open-access. The top field-specific journals, such as PLoS Computational Biology and Bioinformatics are open access, in-fact, I can't think of any computational biology specific journals that are not open-access.
Of the two top journals in the related field of genomics, Genome biology and Genome Research, Genome Biology is fully open access, while Genome Research open-accesses its articles after 6 months.
Of course people in these fields still publish in the top general science and biology journals - Science, Nature, Cell, PNAS; which are not open-access, but it would be very unusual for a computational biologist publishing in these venues not to either preprint on bioarXiv or use the gold open access streams at these journals.
Its difficult to say the field has fully made the "switch" as computational biologists publish all over the place, but publishing close-access with a preprint, Gold access, or putting up an author-version copy on an institutional repository, is very much a community taboo, and would earn you a rebuke on twitter and funny looks at conferences.