Delll Inspiron 3420 Is Extremely Slow.

We can run the Pre-boot system assessment test to check the Hardware functionality.

While holding down the FN key switch on the computer till you see the test running on the screen:

You can refer the Dell Article 266787 on www.support.dell.com

http://dell.to/13qLamu

Let me know if you are getting any error messages.

Would also recommend you to do a system restore and take the system to a prior date when it was working fine. At times it happens due to the updates not being properly installed on the system.

To perform System Restore click on the link below:

http://dell.to/11y6wgI

You can also run Microsoft fixit to troubleshoot on slow performance:

http://go.microsoft.com/?linkid=9740820

Also, please run a virus scan on the system to check if there is any virus on the system.

Please reply for further assistance.

Thanks & Regards
Rathish C
#iworkfordell