7745g heat issues

I bought this Acer Aspire 7745g a couple of months ago, and its a really good laptop, 2.4 GHz Core I5 with ATI Mobility Radeon HD5850 witch allows me to play games at a really high gfx settings..

I do have one problem though... it heats up so much that it actually shuts down, this happends when i do play these demanding games like Dungeon siege 2, Duke NukeEM forever, crysis 2 and so on..

Anyone have any idea on how to minimize the overheating ? I got a Zalman

ZM-NC2500Plus to cool it down, but it still get to hot..

Im considering to replace the heat sink with a more effecient one, and wondered if anyone have an idea on what heat sink would perform better on my laptop..
Of cause it would be best it if fits perfectly, but im not affraid of modding my case and so on if needed..

any feedback would be appreciated

Thanks

 

Changing a heatsink is not an option- you can't fit a bigger one for obvious reasons and just another one won't make the difference.
Make sure that you've cleaned the vents (no dust inside) and you've applied high quality thermal compound.

 

Take it back to the shop...