None? If you have an actual gaming laptop, most of them have air intake at the front or side, not the bottom. So a laptop cooler is not going to do you any good. Most of them are gimmicky products anyway, a fan on the bottom of my laptop wouldn't do a damn thing.
What you should be doing though, is looking for the root cause of why it's running hot in the first place.
It's the Asus Gamers G72GX RBBX05 Laptop edition, every review about this laptop is that it can handle every game except that it overheats very easily so they said if I get a laptop cooler it would make it work easily. This thing gets really hot if I run StarCraft II even on "low" with the lowest dimensions and low quality sound.
Tried using compressed air to clean dust?
Haven't tried that yet, I'll try this.
I would die if i ever got sand into my precious laptop
As it is i only ever use it on solid flat surfaces so the air vents aren't covered. Luckily mine's a factory refurbished unit so the thermal paste had already been re-applied.
I bought mine as factory refurbrished too, people said to update your BIOS and read reviews about the BIOS 602 which is the latest BIOS for my Asus model. They said it is pointless to even try downloading it. So I bought a temporary laptop cooler from Targus again this time a different model. So far it is "okay" but not strong enough to cool it all the way. The fans are pretty weak even at high.
So, I'm going to buy a Cooler Master laptop cooler I just need one that would last over a month seriously lol.
Also the air intake is from the bottom of the laptop and air outake is behind the laptop. If the intake is from the sides it would make it so much better so that I don't need to get a laptop cooler for the bottom of the laptop and leave room so it can breathe.
I might need to do it the old fashion way and leave the air condition on and freeze to half-death for a while then turn it off or something so that my laptop can cool. Thats what I had to do with my old computer.
PS I bought this for $519 + tax which was $579.
This thing has a Nvidia GTX 260M, 6GB DDR2 Ram, except it runs on Intel 2 Duo 2.53GHz.
Edit:
How about this one?
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Has good reviews.