Acer Desktop PC's boot, then shutdown

Hello All,

I have a number of Acerpower f2 computers that are at least 5 years old & they all have the same issue. I can't get them to boot into Windows... When I hit the power button the fan & power kicks on and as soon as that happens it shuts down. It never gets to Windows. I have tried switching power supplies, but that doesn't change anything. Any ideas on what the problem could be?

Personally, I DO NOT like Acer computers , but my employer uses them because they are cheap. It seems like when the warranty expires all sorts of issues arise.... I have had on-bard video, network, and motherboards all go bad within weeks of warranties expiring.

Thanks in advance for any assistance.

Scott