No output on monitor then after 2-3 mins SMPS fan spinning fast.

[Rgironman]

There was an update in windows 10 after restarting the pc the computer won't turn on . There is no output on the monitor and after fews minutes the fan of power supply unit spinning very fast . Also in past couple of weeks my computer performance was degrading like memory loss of ram. High cpu / ram / disk usage.

I don't know where's the problem. 

[itsmyname]

@Rgironman -- I think that your disk-drive has gradually been failing, including taking seconds, instead of milliseconds, for each input/output operation.  Of course, Windows "waits" for each input/output operation to complete, and "freezes" your computer for 100 to 1000 milliseconds for the input/output to complete.

Restart the computer, and choose to launch the HP Hardware Diagnostic.

Run the "short DST" (short meaning about one minute of the Disk-Drive Status Test).

If it "fails", do not run the "long" (many hours) DST.

Instead, replace the disk-drive, maybe replacing an old/slow disk-drive by a new/fast SSD (Solid State Device) and reinstall Windows.

Attach the current disk-drive as a "secondary" disk-drive, to see if you can copy any Personal Files from "old" to "new".