Re: Computer has trouble starting up.
I had a similar problem to yours. *warning, may not be good news* When I went to turn on my computer, it would start, however, it would turn off about 3 seconds later and restart. I wouldnt get a BIOS post either. I also noticed that my power button didnt funtion properly. Instead of just pressing the button once, i had to hold it for 6 seconds for it to turn off. As for the reset button, forget about it. Tested my rig on 2 other PSU's and the same shiz happend.
So, later after I got a professional (my knowledge of computer hardware is pretty good, but this problem baffled me) to troubleshoot my problem, he deduced that my CPU (a Q6600) and motherboard we're toast.
So, what I wuld reccomend for you to do at the least, is make sure your HDD is unplugged, you dont want your HDD header breaking from all the unwanted restarts. Then call a computer hardware professional to come to your place and troubleshoot your problem.
I did the same thing you are doing now, posting on forums for a solution, but fact came and my problem was never solved. Leave it to the pro's, the net cant always help.
Anyways, seems to me that your motherboard has suicided, just hope it hasent taken the CPU or any other components with it(like it did with my Q6600).