i changed motherboard of HP dv600 but when i start the computer but after few second its shutdown. Fan working properly, no beep sound heard, i want to ask you is there any setting in BIOS or is the processor paste or something else.
Another possibility is an incompatibility between your existing PSU and the new motherboard.
Such an incompatibility can produce lots of different symptoms e.g. fans turn but no POST,
almost instant shutdown, auto-restarting by the BIOS, or just simply lights and fans ON
momentarily but then total shutdown in about 1 second.
A shutdown in about 1 second usually means that an input DC voltage is out of range
i.e. defective PSU.
I had a similar problem recently with a new ASRock micro ATX motherboard and
an older ATX PSU: when I changed the PSU to a more modern one, that motherboard
booted up AOK with no other changes: the odd thing was that all fans were turning,
but there were no beeps and I could not reach the BIOS.