Inspiron 3470 - Powering on

Hi all

I was wondering if someone has any ideas about what is happing to my Inspiron 3470 Desktop.

When I switch on the power socket the computer the power comes on as normally I assume it does start up tests, then goes off before you push the on button.

In the last few days when the light comes on it acts as normal by going off then for some reason it comes back on then does the same thing goes off then comes back on. I can't hear the hard drive running until I push the power button then it boots as normal.

Also when I do get into the BIOS the time seems to have reverted to the wrong Date/Time, I was thinking the CMOS battery might need changed but that wouldn't explain the strange behaviour before I press the power button would it?

Thanks in advance

Kelvin