Just raising it helps some, but in general any newer laptop draws air from below and exhausts it from the sides so a cooler on the bottom doesn't do a lot for the laptop.

The exception is if you are resting it on a soft surface that could block vents, like your f-ing lap! In that case any of those coolers will make a big difference in both your comfort and the laptop. On a good hard surface that will make very little difference unless your laptop vents are clogged up as others have said.

I used to have an Asus aspire that would barely run games and overheat in less than two hours, I abused the crap outta that thing. Ended up getting one of those laptop coolers, had one fan in it and some sort of aluminum top. Really the cheapest thing you can find, and it did the trick. So I'm thinking you might be better finding another solution to your issue, something like cleaning the fans, or re-applying some thermal paste if possible.

You are better off cleaning your laptop fans/ vents with compressed air.