Not sufficient, probably.
http://www.realhardtechx.com/index_archivos/Page362.htm
Seasonic probably has extra capacity, corsair perhaps not, depending on the model.
That said, sli gives you wonderful synthetic fps benchmarks.
But, your gaming experience would likely be better with a single strong card.
dual gpu is prone to screen tearing and stuttering.
An increasing number of games no longer support dual gpu.