Uday_Sama

ThrottleStop has a stress test called the TS Bench test. 

 
It will report errors when your CPU voltage is not set high enough.  It also allows single thread full load testing which is just as important as full load testing when adjusting laptop voltage.  Most laptops use a higher multiplier when partially loaded so you need to test that your offset voltage is stable during this situation as well.
 
The ThrottleStop Limit Reasons window reports all of the reasons why a laptop CPU might be throttling, including some reasons that no other monitoring software is reporting.  Intel XTU does not correctly report throttling when it is caused by BD PROCHOT.
 

 

 
HWiNFO is a great monitoring utility but when trying to find out why your laptop is throttling, HWiNFO can be "too much information".  ThrottleStop concentrates on throttling reasons that are specific to Intel laptops.  
 
The latest version of ThrottleStop also lets you adjust the thermal throttling temperature.  Post some pics if you need help.

I want to underclock my cpu to reduce temps. I'm using Intel XTU right now because i can analyse the temps and clocks with the graphs and stress test but it seems kind of buggy.
Many recommended to use throttlestop but i want to have a stress test and stats as like in xtu to know the reason for performance drops temps etc( using hwinfo but it doesn't seem to have continuous data analysis or stress test)
So please suggest some tools to analyze reason for throttling,graphs like xtu and a good way to stress test.
A Newbie here kind of hard to get things right
Please help!

it's just fine but a bit slower

Yeah it will be fine, it will just charge the battery slower.
The heat generated by the laptop and battery will shorten the life of the battery, but it shouldn't be much different from normal since it'll likely run hot regardless, gaming laptop.