Windows 10: Very high CPU and memory usage unless I open the task manager EVEN after factory reset

Hi all i come for help as I've been trying to fix this problem for the past week but I'm new to the PC world so I need help.

I bought and built this PC myself about 4 months ago and it worked fine until last week. The fans started blowing pretty loudly even when doing the most simple tasks and the PC gets way hotter than normal and as soon as I open the task manager the CPU and memory even disk sometimes are at 30-70% usage for a second then they go back to normal levels. Even weirder the percentage shown at the top of the task manager dont match the usage of processes running at all, and when playing video games I have no in-game performance problem, but things like discord or google stop working completely. At first I thought I had a virus so I tried running complete scans with avast and windows, then I tried a rootkit scan with malwarebytes and finally an offline scan with windows. Problem was still there so I tried a factory reset, still it wouldn't go away so I reset my pc and downloaded windows from a USB drive so now I don't know what to do.

Specs :

CPU : Intel Core i5-9400F 2.9 GHz 6-Core Processor

Motherboard : MSI MAG B365M MORTAR Micro ATX LGA1151 Motherboard

Memory : G.Skill Ripjaws V Series 16 GB 2x8 GB DDR4-2400

Video Card : Gigabyte GeForce RTX 2060 SUPER 8 GB WINDFORCE OC Video Card

Storage: Crucial P1 500 GB M.2 NVME Solid State Drive

:)

 

Task Manager High CPU Usage

I have the same problem myself with it only happens when I scroll through task manager and open and close it. I don't know this for sure but the reason this probably happens is that you may have a lot of processes running and task manager is using a lot
of the CPU to process the usage of each program.

What I have done is disable data that I don't need to see like network usage and GPU usage and it drops the CPU usage a bit. I have also enabled everything and scrolled up and down on it and task manager uses almost twice as much.

I would suggest disabling everything but CPU, disk, and RAM, (I would not suggest having GPU on because it is almost always at 99% unless you have FPS limits).

 

High CPU usage when opening task manager

Hey, so as said in the title, my CPU usage is unusually high when I open task manager. After about a second, the CPU usage starts dropping down to around 5%. I've ran malwarebytes multiple times, but the issue still persists. I would like to avoid resetting
my PC if possible.

 

High CPU usage unless task manager opened, but no rootkit detected

I am using Windows 10 (v1903). Whenever I open Task Manager, I see that CPU usage is at 100% -- but then it plummets to ordinary numbers (typically below 20%). This change happens so quickly that I cannot see what task is using so much of the CPU.

The problem seems like the one described in Windows 10 high CPU usage unless task manager is opened. But I have tried the advice given in the answers to that post, and the problem persists. Which makes me wonder whether it is a problem at all. Specifically:

• The following software has turned up no serious problems: MalwareBytes (run from my normal boot drive and again from Hiren's BootCD), ESET online scanner (run from Hiren's BootCD), Norton Endpoint Protection, and McAfee's rootkit detector.
  
• When I use Process Explorer to gauge CPU usage, I don't see a problem. Most of the CPU usage in Process Explorer is attributed to "System Idle Process."
  
• A Windows Defender offline scan just runs, stops for a reason I can't discern, and reboots the computer. It doesn't leave an entry in the "Protection history" section of the Windows Security app. It does leave a log file saying that "On demand scan closed without completion."
  
• GMER rootkit detector crashes with a BSOD, even when run in safe mode and when Windows' built-in virus and threat detection are disabled.
  

Is there a way to identify the process using so much of my CPU? Or should I simply conclude that the Task Manager results are more suggestive of a nuisance than a real problem?