Suddenly all Games and videos lagging Stuttering after update windows 10. Plz help!

I have no answer for you.
I have seen other recent similar posts after a windows 10 update.
Since you also tried windows 7 and 8.1, the OS is not likely the cause.

4gb is a bit small for a 64 bit OS. I think you might do better with 8gb.
One possibility for the sudden change might be a problem with your hard drive.
WD has diagnostic programs called data lifeguard that you might run.

Regardless, I would really try to use a ssd for windows.
Samsung even suggests that it helps lagging and fps:
http://www.samsung.com/global/business/semiconductor/minisite/SSD/global/html/why/forGamer.html

If your computer is stuttering and lagging, as per your description, no matter which version of Windows you are running, it's probably due to the hardware. Make sure your machine is reasonably free of dust in areas such as the DIMM sockets where it can on rare occasions cause memory errors and also that no parts are overheating, which can manifest as poor performance caused by throttling of the components.

Try doing a clean install.

Number of fans are not an indicator of temperature.

Have you actually looked at temperatures yet?

Edit: yes, you've said they're fine, but it would help us to rule them out if you listed them, as not everybody agrees what fine is.

At idle, your temperatures in the bios should be 10-15c. over ambient if your cooler is mounted well.
If it is significantly higher than that, it is likely that your cooler has come loose or was not mounted well.
If you used the intel stock cooler, verify that all 4 pushpins are through the motherboard and locked.
If you nudge the cooler, it should not wiggle.
My stock advice on how to mount a stock intel cooler:

----------------how to mount the stock Intel cooler--------------

The stock Intel cooler can be tricky to install.
A poor installation will result in higher cpu temperatures.
If properly mounted, you should expect temperatures at idle to be 10-15c. over ambient.

To mount the Intel stock cooler properly, place the motherboard on top of the foam or cardboard backing that was packed with the motherboard.
The stock cooler will come with paste pre applied, it looks like three grey strips.
The 4 push pins should come in the proper position for installation, that is with the pins rotated in the opposite direction of the arrow,(clockwise)
and pulled up as far as they can go.
Take the time to play with the pushpin mechanism until you know how they work.

Orient the 4 pins so that they are exactly over the motherboard holes.
If one is out of place, you will damage the pins which are delicate.
Push down on a DIAGONAL pair of pins at the same time. Then the other pair.

When you push down on the top black pins, it expands the white plastic pins to fix the cooler in place.

If you do them one at a time, you will not get the cooler on straight.
Lastly, look at the back of the motherboard to verify that all 4 pins are equally through the motherboard, and that the cooler is on firmly.
This last step must be done, which is why the motherboard should be out of the case to do the job. Or you need a case with a opening that lets you see the pins.
It is possible to mount the cooler with the motherboard mounted in the case, but you can then never be certain that the push pins are inserted properly
unless you can verify that the pins are through the motherboard and locked.

If you should need to remove the cooler, turn the pins counter clockwise to unlock them.
You will need to clean off the old paste and reapply new if you ever take the cooler off.
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Have you looked at a graph of your CPU and GPU usage and clock speeds before and after the stuttering occurs?

Might try something like MSI's Afterburner software, to see if your clock speeds are fluctuating out of the ordinary, and if it correlates to temperatures.

If this works, I'm going to track you down and kiss you on the lips.