Official XS Power Supply Ranking Phase I

[Source]

That's an very nice PSU yes.

Might be above Tier 2.
The HX on Perkam's list is the old one (HX620 and HX520), not the new models.

52A / 624Watt on the 12V

Most people would think that the HX650W is merely an upgraded version of the very popular HX620W unit and that may not be far from the truth. The specifications however of the HX650W are considerably superior to those of its 620W counterpart and it also comes with an 80Plus Bronze certification and a 7 year long warranty.

As for an review: http://www.hardwareheaven.com/review...onclusion.html
He get's an 9.8 / 10,

And for an review of his bigger brother (HX850): http://www.jonnyguru.com/modules.php...tory3&reid=153

Plus, the 7 years of warranty is also a nice touch.