I want to know how much time should be left before replacing motherboard ,ram,hdd,cd rom and reconnecting them from turning of power supply.Some time should be left to cool down.But how much time? Is there any risk of electric shock if touched immedialtely after turn off and disconnect all cables(peripheral and power)
Not sure what you are trying to do here? When you open the case up, Always unplug the power supply cable.. Then push the start button to discharge it.. Now you should be good to go..
You can 1. turn off computer 2. unplug the cables from the wall outlet and the psu cable from the psu 3. touch the psu 4. go do your thing