update drivers, they can be the cause of memory leaks
In the performance tab of task manager, click on "Open resource monitor" at bottom of screen, open the memory & HDD tab in the next pop up, and see if it shows what is using either
can also download process explorer - its an op version of task manager: https://technet.microsoft.com/en-us/sysinternals/processexplorer.aspx?f=255&MSPPError=-2147217396
this explains what it does and what colours mean - link at bottom of page shows how to use it to find memory leaks: http://www.howtogeek.com/school/sysinternals-pro/lesson2/
if you open it, click on the header marked process twice and it puts it in tree view, this will show you the order of the processes and show which is using most.