kingyu :
I recently RMA'ed my m2 720w, but the customer service said they don't have any 720w in stock, they sent me a "upgraded" silent pro m 850w. I don't know if I should keep it or ask them to resend me the m2 720w when they have it in stock. Thanks
Well, probably keep it, but the m850 is a discontinued unit and the OEM is FSP,
the m2 720 is still current(Haswell cert) and OEM is Enhance Electronics, and is slightly more efficient.
With that said, I'd see no negative issue to keeping the 850. And should you decide
to CF/SLI 2 high end GPU's in the future, you'll have enough PSU power.