If your new Acer Aspire 7551G keeps overheating, it is probably due to the fact that the BIOS whose main duty is to keep both CPU and GPU cool, is only keeping an eye on the temperature of CPU, ignoring GPU completely.
So to counter this problem, a forum user, made an application that note only keep track of CPU temperature but also of GPU. Download links are given at the bottom of this post. Here are the installation instructions for the app.
First install the TVicPort and copy the Acer7551GFanControl.exe on your desktop. Then config.xml to the same directory as the exe. Feel free to create a shortcut to Acer7551GFanControl.exe in Start > All Programs > Startup. It is being said that it will work with other laptops but the developer does not guarantee anything.