400 w is extremely high for that amount of space.
if u dont have the right ventilation, with venting tubes, multiple fans, cooltubes, youre gonna be in a lot of trouble.
you might want to look into a 250w and get a couple extra mini lights if need be. if u look on eBay, ofc all the sellers will shout "400w 400w is the way to go" but theyre trying to move product. 400w is neither the median nor the the average light needed because everything is based on grow size. and if ur overheating ur plant, ur yield will def suffer.