I do not think this is a common problem in the G771 series but throttling down to 800 MHz is a common problem for many previous generation Asus laptops. Asus is not the only manufacturer with throttling issues. It is an industry wide problem.
If I saved up and paid top dollar for a laptop, I would be very disappointed if I found out that it was only running at 800 MHz. That is ridiculous. On some models, a simple bios update can fix this issue so make sure you are using the most up to date bios version. On other models, it might be the sign of a bad sensor on the motherboard and the motherboard might need to be replaced. Sometimes it is just poor design and besides running ThrottleStop, there is nothing else that can be done.
What are your options? If it was a brand new laptop I would consider returning it. If you really like the laptop overall and it has good cooling like many of the Asus ROG laptops have then your next option is to run ThrottleStop so you can better manage this throttling problem.
ThrottleStop is designed to run your Asus G771JM CPU within the Intel specification. Intel never, ever intended their performance CPUs to be throttled down to only 800 MHz. Intel designs their CPUs to deliver maximum performance right up to the thermal throttling temperature which Intel sets to 100C. The throttling you are seeing is usually not triggered by the CPU temperature. There is usually another temperature or power sensor on the motherboard or in the power supply that signals the CPU to start throttling. Using ThrottleStop to disable BD PROCHOT blocks these signals from getting to the CPU so your CPU can continue to run at its full Intel rated speed. No matter how you have ThrottleStop setup, it will not force your laptop to run at full speed if the CPU is over heating. Intel has done a great job of protecting their CPUs at the hardware level. If they get too hot internally, they will throttle and slow down to protect against any damage.
Start doing some Google searches. Add up how many different laptop models from different laptop manufacturers can benefit by using ThrottleStop. This program is used world wide because it is the one and only freely available program that can fix these throttling issues.
Now do another Google search and try to find users of ThrottleStop that have damaged their laptops because they used this program. Considering the huge boost in performance that ThrottleStop can deliver; it is extremely difficult to find users of ThrottleStop that are not 100% happy with their decision.
I will be honest. I am the guy that wrote ThrottleStop. If computers were being damaged because of this program, I would know about it. People would contact me to complain but in the many years of development, that has not happened. No individual or large corporation has threatened to sue me. I kind of think that Asus, Dell, Lenovo, etc. are all happy that users have an option to fix these throttling problems and it doesn't cost these companies one cent. It would have cost them far more if hundreds of thousands of laptops were returned because of throttling.
In my opinion, Furmark + Prime95 is an excessive load for any laptop. I only recommend using ThrottleStop while gaming and only when plugged in.
ThrottleStop 8.00
https://drive.google.com/open?id=0B0dpSo9k93jDTE1fcHNtbUMwdGc&authuser=0