PC wont turn on

We are currently running 300 workstations, 190 of them use ONE model (Gateway E4620). There are some that had same problem (about 20). Initially it works great until a while later, it will not power on. I had to unplug the power cord and plug it back in then I will be able to power on. The staff have to do that every time.

What is the possible cause? What should I look for to get it FIXED?

 

I would start first by purchasing ONE new power supply with sufficient wattage, amperage, and if possible dual 12V rails. Replace one of the workstation's PSU and see if the problem remains. If the issue is fixed after a bit of trial and testing, order more PSUs for the remaining systems and replace them.

That's a start...next culprit if the PSU isn't the issue, is the mobo(s).

 

I've had that happen with systems that have bad capacitors on the motherboard. Look at the tops of the capacitors for bulges or even any leaking electrolyte gell that has popped it.

You can always hold the power button and count six (let's say eight - some people count faster than time moves) seconds and that should shut it off. That way the employees do not need to pull the computers out from under their desks.