My pc won't star but light on mother board is glowing

[anurag punk]

Hello,
my pc won't boot whenever i try to turn on my pc nothing happens no lights , no beep sounds , no hd light only one yellow light is glowing on motherboard , from 4-5 days my pc was causing problem , whenever i started my pc it would run for 2-3 minutes and gets off by itself but sometimes it would run for 4-5 hours without getting off and my cmos battery was also faulty at starting it says ' press f1 to go to setup and f2 to load default values ' but i don't think it has something to do with it so please help me guys

my pc specs
Intel core 2 duo E7500 @ 2.93ghz
mobo- asus p5kpl am in
ram - 2gb
hdd - 320 gb

 

[hefox]

Take the ram memory out and see if you get any beeps. Do you have any fans running when you turn on your pc? Also make sure the cpu heatsink sits properly.