FPS not stable,

Anyone have any idea what's happening?
Had no problems the past few days, only started yesterday after i started using a laptop cooler (Cooler Master U3) which i'm sure couldn't be the problem.
Even after i remove the laptop cooler it still happens. With CS:GO i can see the FPS now and then drop to 30-60+ while most of the time it would be 100+ average
Even with Heaven benchmarking, FPS would usually be 100+ but now and then drop to 30-60+ as well...

I installed MSI Afterburner with Rivatuner few days ago, and had no problems then. But the problem only occured yesterday. I read some had problems with FPS drop with MSI/Rivatuner. After uninstalling those apps it didn't make much difference.

I also changed Nvidia global settings to high performance Nvidia Processor, and also power management to Prefer maximum performance but still no difference.

The last resort would be to re-format my hard disk/windows... which i'd prefer not to unless there are no other solutions...

Btw using:

ASUS ROG GL504GM
i7-8750, 8gb RAM, GTX1060, 256gb SSD + 1TB SSHD