IF he uses a "not that good PSU" to feed 12V on the VCore Mos-fets, this could happen...."Spikes" will travel through the PSU to the Mos-fets and cause them failure.....
I have ONLY TWO PHASE circuit here and I can draw EASY ~225Watts....

Also I want to inform you something about efficiency on them.....The hotter the go, the LESS efficiency you get out of them....
You'll get LESS efficiency is the Mos-Fet works without a heatsink at - ex. 95*C and you get more if it works at ex. 50*C....