Be Quiet B8 550W vs Corsair CX 550M

BeQuiet doesn't make PSUs. they don't have the resources to do so, like many other brands (EVGA, Corsair, XFX,..)
so they buy designs from PSU manufacturers, combine them with some things they're good at and change a bit and then sell them as their own.
BeQuiet rebrands units from 3 different manufacturers: Seasonic for their Dark Power series (although I think they switched for the last one), FSP for their latest Straight Power line and HEC for the lower series
different manufacturers have different skillsets.
Seasonic only does high grade stuff. they always use high grade japanese capacitors, integrate all safe guards, use redundancies and so on. the cheapest Seasonic unit you can find is still a very decent PSU.
FSP has a variety of units, some are lowgrade, some mediocre, some are actually pretty good.
HEC usually only does cheap stuff. mostly not dangerously cheap, but cheap. cheap chinese caps, no redundancies, bare minimum for a reasonably save and stable PSU.

As for group regulation: the PSU gets supplied with 115V / 230V from your outlet and regulates this to 12V / 5V / 3.3V
group regulated means basically (and overly simplified) that all of these voltages are regulated by one part directly from the incoming current. this is how PSU have been made for many years.
by now this design is outdated. currently it's done by adding DC-DC converters, basically meaning that the incoming current is regulated to 12V, then there is essentially a second PSU in there, that regulates the 12V current to 5V and 3V. A PSU within the PSU if you want.
this has some advantages, espacially with crossloads. power delivery is cleaner, the unit can supply almost all of it's power at 12V other than the group regulated PSUs. downside: it's a bit more expensive bcs of the extra parts needed.

this is pretty simplified and I'm sure not 100% accurate but I think it's understandable...


Seasonic M12II / Evo were good PSUs, but they're getting old tbh.
they are Seasonic, so safe, good quality and last forever.
their performance was great when they were released by now they're a bit dated.
I'd rate them around the same as the new Straight Power 10 and the 2016 Corsair CXM. They use a bit better parts but perform not as good (in terms of voltage regulation, ripple, noise)