Not sure how old the machine is? It's more than 3 years old I, a fresh thermal paste application would be certainly help. 

Did you change any settings in BIOS for this windows installation ? If no please reset BIOS to default it helps 

1. Reboot to BIOS > Performance > Turbo Boost > Turn it off

2. Install Dell power manager from store (set to Cool profile) 

3. Do you keep power cable connected while using it on Lap : Reduce performance mode to battery saver (Click on Battery Icon on Task bar and move the silder) 

have tried these before no luck , no i don't use while power connected,  already on cool but even on teams for windows cpu goes to 70

It's a year old but disabling turbo boost causes performance issue while using normally I specifically want it go on low performance when using in lap which was happening before i manually flashed windows.

On the lap : do you keep power cable connected ?? 

I usually don't do it. Change performance settings in dell power manager to COOL 

Change battery performance sliver more towards battery saver. 

Power plans are part of Dell's Customized Factory image 

How did you reinstall windows 

If you use windows RESET feature of ISO from Microsoft ,those options would be gone. 

You can do a factory image restore using Dell OS Media. 

Use a USB and this tool to create such media

https://www.dell.com/support/home/en-us/drivers/osiso/recoverytool

Do you know way by which i can get the dell power plans back there is only one option in my windows now that is balanced