If you open the Windows Task Manager, you may see a process csrss.exe. This is Client Server Runtime file, and it is a Windows operating system file located in the System32 folder. So what is this csrss.exe? How do you know if it is a virus or not? Why does it consume high CPU on Windows 11/10/8/7 at times and what do you do about this?
What is Client Server Runtime or csrss.exe process
The Client Server Runtime process has a long history. Prior to 1996, the process managed the whole graphical subsystem, while as of present it is restricted to a few critical processes like shutting down Windows and initiating console Windows.
CSRSS stands for client/server run-time subsystem and it must be running at all times. Earlier Client Server Runtime drew Command Prompt, however, since Windows 7 was launched, the function on the process is limited to launching the conhost.exe process which in turn draws Command Prompt.
Can we terminate the csrss.exe process?
The Client Server Runtime process has limited functionality for Windows systems as of present, however, that limited functionality is critical. You cannot kill the process and doing so forcibly would make the system unusable. It may shut down the computer automatically.
However, the process has no reason to over-utilize system resources and since it runs in the background, it shouldn’t bother you for any reason.
Is csrss.exe a virus or trojan?
The original Client Server Runtime process is located in the C:\Windows\System32 directory. 
In case the file is not located at the intended location, it could be possible that a virus or malware is using the same name. Please run an anti-virus to perform a full system scan.
To reconfirm, you may right-click on the file once you open the folder and locate it and check its Properties.
It should be noted that if the csrss.exe process causes high-CPU usage, it could probably be a virus.
Do I need csrss.exe on my computer?
Yes, you do need csrss.exe on your computer as it is a Windows OS file. You cannot kill the process and doing so forcibly would make the system unusable. It may shut down the computer automatically.
Why do I have two csrss.exe files running in Task Manager?
It is normal to see two csrss.exe processes running in the Task Manager even when you are the only person logged in. But to be sure, you can check their file locations and run an antivirus scan as well. The image above is from my single-user PC and you can see 2 processes there.
Hope this clarifies the matter.
Want to know about these processes, files or file types?
Windows.edb files | WAB.exe | ctfmon.exe | Nvxdsync.exe | Svchost.exe | RuntimeBroker.exe | TrustedInstaller.exe | DLL or OCX files. | StorDiag.exe | MOM.exe | Host Process for Windows Tasks | ApplicationFrameHost.exe | ShellExperienceHost.exe | winlogon.exe | atieclxx.exe | Conhost.exe.
