Windows 10: New NVME Running at HALF Speed - What could be the cause?

I just installed a new Sabrent Rocket 4TB NVME (TLC) in the slot where I used to have my WD SN750 1TB benchmarked at approx 3500MB on Read. This slot does not share its bandwidth. Its a simple swap and the Sabrent should be hitting those marks too but it is scoring only half of that... so approx 1750MB.

I've put in a support ticket but am wondering if anyone might know what could be causing this, or what a solution might be.
Or if this means it's defective? What do you guys think?

:)

 

Cpu running half speed

While playing a game few hours ago I noticed my computer suddenly became incredibly slow. The windows task manager showed that the cpu was using half its capabilities. I have been playing this game since 4 years, with this same 4 years-old laptop, and it had never happened before. I have to mention I installed windows 10 few days ago, which also changed my graphic card's drivers. I suppose it is a feature preventing CPU overheat. It may be a new feature, changed parameters that enables it sooner than before, or dust accumulating past 4 years that activates it sooner than before as @Bokan's answer suggest.

The problem is that this feature does not get disabled when I quit the game, making the computer unusable for several hours. When I first posted this question I had to wait about 8 hours before it came back.. by itself. The only other way to get this speed back is to restart windows in any safe mode, but that is not very satisfying. I have checked battery and power parameters, they are not changed and changing them does not restore the cpu speed. I have checked the graphic card's parameters, same.

What is this feature ? How to disable it or change its parameters ?

NOTE : I have an intel CPU that has the SpeedStep technology. But the normal speed is not back after reboot (as I read it does when SpeedStep reduces it), I do not see any option to enable/disable it in the BIOS, neither on the GPU desktop UI. Last time the normal speed was restored while the computer was active (see comments).

EDIT : I just completed the first reboot of the second time this problem appears, and this time it disappeared ! This is madness.

This question has also been asked on answers.microsoft.com :

• windows 10 only use half of max cpu speed
  
• slow processing speed
  
• my pc is running rly slow after the windows 10 upgrade
  
• slow laptop after windows 10 upgrade
  
• cpu not running at maximum frequency
  

You can admire how microsoft does not care about giving the **** name of this feature to its unanimous customers, not even mentionning speedstep or battery / power / cpu parameters.

Also on other website, mentionning speedstep :

• lenovo
  
• tomshardware
  
• tomshardware
  

Here on SuperUser but does not solve my issue :

• What regulates Intel SpeedStep CPU throttling? Can I get some control of this on Windows7?
  All my battery parameters, graphics parameters, power parameters are set to maximum/high/100%
  

On 'Answer Tech', live Microsoft's technicians all answer the same epic crap (they all prefer blaming the manufacturer, asking the customer to return his computer (!!!!) than answering that they do not know). This one was particularly good :

 

Is My Memory Running at Half Speed?..

Nah. This is just to make sure your memory is running at the speed it is listed at. XMP is CPU-only.

 

CPU Running at half speed

That just speed stepping....It lowers your clock settings to save power when you dont need its full power!!