It sounds like your fans are working hard. This means things are getting too hot. Considering it's been 7 years since you got this computer, your CPU could need a new application of thermal paste. That stuff will turn to dust over time, and it'll interfere with cooling.
It might be a power supply issue, because those don't last forever either. I'd check CPU and GPU temps first though, MSI Afterburner is a program you can use for this.