Kernel_task eating up RAM in El Capitan

[sylvirgro]

I have an early 2009 24 inch iMac. Yes, I know it's getting old, will probably get a new one next year. But for now, it is working very slowly due to a kernel_task in root that is using up 700 MB or more of memory according to Activity Monitor. Lots of beachballs and things load slowly. It's running OS 10.11.6 El Capitan with the latest updates. Has 8 GB of RAM installed.

I have reset the NVRAM, the SMC, run Disk First Aid in recovery mode, run EtreCheck (which found suspected adware from 2010, which it removed), and have installed TechTool Pro 9. Spent several hours today running the suite of computer checks using TechTool. Everything passed. RAM is fine, no bad blocks, etc etc.

However, I tried to start up from the eDrive partition installed by TechTool and it doesn't work. It shows up as an option upon restarting with the option key held down, but after selecting it, I get a circle with a line through it and then it starts up from the regular hard drive. Also won't start up from a USB drive (128 GB) with TechTool Pro and Mac OS X Basic installed following the instructions to make it bootable.

Any suggestions of what to try next? I was thinking of reinstalling El Capitan in recovery mode to see if that would help.
Sylvia

 

[chas_m]

What happens if you just kill the rogue process using activity monitor?

If it shows up after restart, it sounds like it is a problem with an outdated background startup background item. I would look carefully at your account system preference pane and delete Startup items that are no longer needed or have a ! Next to them. If you need help, post a screenshot of the startup items here and we'll offer advice.