Antec is Multi Rail 12V PSU, Corsair is a Single Rail 12V PSU....
You need to manage your load distribution to maximize the usage/capacity of multirail PSU.
On Single Rail all 12V are supplied by one source. That entire 840W is available. Just connect the load.
My personal recommendation is go to single rail... There is a long list of pros and cons bet the 2 types.
All my last PSU acquisition since 2009 are single rails 12V type PSU... Corsair HX850 and Corsair HX 1000... These days the newer models are the AX series from corsair.