I answered your post in the Computer Help forum (http://forums.cnet.com/7723-6122_102-623709/power-to-pc/?messageId=5598023#message5598023), so I'm locking this one.
It could very well be a hardware problem indeed. Then replacing the faulty component (not clear if that RJ45 is on your motherboard or on a seperate card) could be the solution.
My english is not good sorry for the mistakes.
CPU details are dx2280 dual core p4
When i put on the CPU it ll not getting start but when i remove rj45 connector from CPU, it gets start. Each time i have to do the same. How to recover the problem?