Dell Inspiron 5577 i7 overheating Problem...

I am using this laptop around 2 years and I am facing the heating problem around last 1 year. For fixing this issue, I undervolt it (Core offset -145mV) and disable turbo boost which is not worth it. I tried my best to fix this issue, I updated all the drivers, bios. But while gaming the cpu temperature reach upto 90 after undervolting and disabling the turbo boost. I don't know why dell is not providing us to control the fans. Fans starts spinning when the temp reach at 70. Now my system is also crashing. 1 year ago, I contact to dell support when my laptop was in under warranty that I am facing overheating problem. They remotely run a system test and there is no issue. But the temp are going upto 100 while gaming at that time I had no knowledge about undervolting.