Hi do like this to sort it out:
Check which processes and services that is most demanding, to see if something strange going on:
Start > type Resource > click Resource Monitor > open up the window so you better can see > click Overview > make sure that you can see both Processor and Disc windows.
and then sort by clicking the CPU column (in both windows) and make sure that the very tiny arrow point downwards - it will sort all the most demanding processes with the highest from top > Take a screen shot of that.
Then click the processor tab so You also can see Services, sort on the CPU column so the little arrow points downwards.
I suspect a memory leak problem from a poor written s/w or a driver, and then it has nothing to do with the memory's or possible that Your computer has been infected with a very nasty virus.
Best regards from Sweden