MacBookPro: How hot is too hot?

I have a 17inch MacBookPro with Retina Display, model A13898.

I do both professional video editing and plenty of gaming on my laptop.

When I play games, edit video, or even watch youtube.. my laptop starts to heat up. I know that it is normal for the metal casing to become too hot to safely touch. I have a 3 fan cooling pad running beneath my laptop, and this barely helps, so I have to use ice packs from the freezer when I play games.

In a few -very rare- instances, my laptop has heated up so much that my fingers get slightly too hot (slight burnt) even on the plastic keys!

I've had to have my power adapter replaced twice (imagine the second Apple Genius' shock when I came in!) since I bought this MacBook in mid 2014.

The bottom of the laptop and the space between the keys and hinge are what get the hottest.

I understand that Apple does not want us to use a third party apps to check the internal sensors because this does not measure the external casing temperatures. However, doctors also tell us not to use WebMD to self diagnose, and we all still do it. I downloaded an app to check on the temperatures of my CPU and to make sure my internal cooling fans are still running properly.

Even with just a web browser open (multiple tabs, not excessive, not all loaded), my CPU core is operating at a temp range of low 111 to high 125 degrees Fahrenheit. This is a concerning number and I couldn't find a chart of "normal operating temperatures." When I play games, this number range jumps to a low of 141 degrees F and I'm unsure of the high.

My left fan appears to be working significantly harder that my right fan.

How hot is too hot? How do I know if my graphics card or CPU is about to fry?