PC keeps rebooting

[Yegorov]

Hi, my computer was rebooting non-stop, it showed the motherboard screen (the one which tells you to press DEL for bios etc..).
I disconnected DVD and HDD and also tried with a new power supply and it didnt change, so i changed Motherboard, CPU and RAM and it keeps doing it. (New: AsRock h81m-vg4, Intel g3250 and kingston kvr13n956 2gb)
So.. i tried with new (again) CPU mother and ram (new: MSI H81M-E33, Intel g3260 and crucial 2gb ddr3 1600) and it keeps rebooting for ever.
i also tried with a LOT of rams and keeps rebooting
i just cant get whats happening..
sometimes i can open bios but it reboots before i can see something
changed asrock to msi and kingston to crucial, cpu is the same, just different model, maybe hole intel g.. are bad
any help? thanks!

 

[popatim]

Have you checked or tested the power & reset switches?
While the system is in the Keeps Rebooting phase you could take one off and it still reboots then take the other one off.
If it still reboots then take it out of the case and try.
Still reboots then try another PSU