Since you have an Intel Haswell CPU you might as well get a Haswell compatible power supply unit.
The Seasonic S12II Bronze 620W (SS-620GB) and M12II Bronze 620W (SS-620GM) are not Haswell compatible since they're built on an older group regulated circuit design.
You would need to get the M12II Bronze 650W (SS-650AM) model that is confirmed to be Haswell compatible since it's built on a more modern DC-to-DC circuit design.
Since you have an Intel Haswell CPU you might as well get a Haswell compatible power supply unit.
The Seasonic S12II Bronze 620W (SS-620GB) and M12II Bronze 620W (SS-620GM) are not Haswell compatible since they're built on an older group regulated circuit design.
You would need to get the M12II Bronze 650W (SS-650AM) model that is confirmed to be Haswell compatible since it's built on a more modern DC-to-DC circuit design.