First of all the problem started when i tried installing Wireless network adapter to my PCI slot. Before installing the adapter i shut down the computer and placed the adapter into PCI slot,a and i tried turning on the computer but it didnt go on for some reason. Then i removed the adapter and tried turning the computer on and computer worked normally. After that i tried placing the adapter in PCI slot while computer was on, and as soon as i placed it in to PCI slot, pc shut down straight away and wouldn't open again. Even, if i remove the adapter from PCI slot. Now when i try to turn the computer on it goes on for about 2 seconds and shut downs again it keeps doing it till i unplug the power cable. I Think that the PSU wasnt powerfull enough to run the network adapter so its gone bad? Tried removing the graphics card and Ram on the pc and see if it works but it didnt work either. Once when i was trying to open the pc luckily went on but it did not show anything on the screen and fans lights etc were working fine(that didnt happen again though). I have bought new corsair gs 700 PSU but the problem is still not solved. What do you think its causing this problem??
Thanks for your respond das_stig,
i cant return the motherboard to them because its over 1 year warranty period. I think i am going to change the motherboard in this case. Which motherboard brand you recommend ? i found this one http://uk.asus.com/Motherboards/Intel_Socket_1155/P8Z68...
and i think i will be getting this one. I hope changing the motherboard will resolve this problem, it is really frustrating.