Reduce gpu temperature

There really isn't a whole lot you can do, at least in comparison to what you could do on a desktop. However, you can ensure that all of the heat ports are clear of dust and debris by spraying them out with a can of air every now and then. You can also ensure that you use the laptop on a flat, hard surface in order for the heat to better escape. Finally, it may be worth while to look into a USB based notebook cooler to bring the temps down a bit.

If it is still under warranty, you can also call HP and let them know of the issue and perhaps they'll do something about it. If not, you can complain to them never the less. I had an HP laptop a few years back that lasted a little over a year because of excess heat, i.e. heat is a laptop's worst enemy.