Booting problems

[Proverb76]

Hi, im new here so forgive me if this post is in the wrong place or has already been answered somewhere else.

I have been having problems turning my computer on and wondered if anyone knew why this be happening.
When i turn my computer on in the morning i hear the fans start up but nothing else seems to happen, after about 5 mins i press the reset button and everything works fine. When it is first turned on i press the reset button but nothing happens, i have to leave it for at least 5 mins before i can press the button to get it to work.
I have tried replacing the power unit but this hasnt helped the problem.
Any ideas??

Thanks in advance.

[Mt_Goat]

Could you please provide the details of your hardware? Include motherboard, CPU and cooling, memory, video card(s), power supply and anything else in your system.

[Proverb76]

I can try lol
Pentium 3 864mhz, 512mb ram, Fujitsu mpg3204AT 40gb hard drive, wdc wd400jb 20 gb hard drive, Nvidia geforce fx5200, 650w High Quality, Dual Fan ATX PSU. Im not sure if thats the info you need. Im also not sure how to find out what motherboard or cooling system i have. Sorry im a bit thick when it comes to this sort of stuff.