As best as I can tell the only authoritative collection of the works of Archimedes containing the original Greek is that of Johann Heiberg, "Archimedis Opera Omnia cum Commentariis Eutocii" (1880). There is, of course, the Loeb Classical Library volume (1962), but that only has a selection of Archimedes, not all of his works.
Is there any edition more modern than Heiberg's that has the original text of all Archimedes works?