I also have the Asus G73JH.
First off, it's a good laptop. But I had to take it apart because it was overheating. And let me tell you this - don't ever take this laptop apart. It's a freakin nightmare!
I was able to put it back together - but was not able to fix the overheating problem (although turning off TURBO in the BIOS did help). It has kind of terrible cooling system inside this laptop ( I believe the CPU is cooled by...the keyboard, which is totally messed up in my opinion).
I have read reports of a bad GPU (5870) of which some people got (screen going white, gpu showing pixelation on some games).
Also I noticed my laptop overheats if I don't have it in a properly ventiliated area (which cause it to shut down). I also have the underneath part very well ventilated (propped up with a some wooden stands).
Is your TURBO turned off in the BIOS? I had to turn mine off as my laptop gets way too hot if I have it on.
There is also a GSOD issue with some laptops. You may want to take a look here:http://www.btoforums.com/showthread.php?t=2735
Maybe try updating your VBIOS.