thisThis is a fairly old question but I have a rather unique solution. Buy a good laptop fan just for the power brick, it wontwon't provide so much cooling that it will cause damage but will keep it running at a reasonable temprature. I own both an AsusASUS ROG gaming laptop and an Alienware one as well. Both power supplies have heat issues.
Personaly I use a box fan leaning at an angle against the wall and I have made a support to hold the psu against the fan. This keeps it very cool.
The picture I attached is an older setup in which I used the power cables size to hold it on the fan! (also the psu has feet which fit in the fan notches