I am running Hitec HS 65 MG servos on my align 450 pro with a 3gx system. When powering up the ESC gets very hot after a couple of mins then the system shuts down and the servos get hot as well.
Sounds like something is under a high load and it's straining the BEC inside the ESC. If you have one, or can get one, I would get a watt meter that can measure how many watts a servo pulls and check each one of them. I will almost bet they are pulling more amps than the BEC can handle. I suggest this tester, it's the one that I have and it works great.