Is this memory compatible with the Asrock Z77 Pro3? I think it should, but I'm not sure. It isn't listed on the supported memory list on asrock's website too, although I suspect they don't update it too often, and that it isn't complete.
More aboutcorsair xms3 cmx2gx3m1a1333c9 compatible asrock pro3
Here's the list of tested memory. This memory may work though.