won't boot for the first time

this is the first time that this is hapening to me.when I bot the comp for the first time(you know,push the button),the screen is just black(hdd led is on all the time,fans working ,but hothing else.so I must push restart button,and then it's give me bios boot failure,and to go to bios and set to default.after that everything is ok.But when I turn off the comp for a long period(say 4-5 hours) the comp[ give's me the boot failure again.I reset everything,check the ram wth memtest.everything is ok.mobo is p5n-e sli,and comp is 5 mounths old.nothing is O.C,so I suspect that the battery is finito,but I want your oppinion for this matter.THank's in advance.

 

that would be my suggestion in a computer thats at least 5 years or older....something else might be wrong with yours, have you flashed your bios on the motherboard recently? if not, maybe you need to?

 

thanks thesmokingun,and yes don't flash the bios so far so when you tell me about flashing,I did it instantly,and tomorrow will see ehat will happen.Thanks again

 

Good luck,Sarge.

 

it's happen again."warning:system boot failure".I forgot to mention that computer freeze on bios post and everything I can do is to push the restart button.After that it's ok.My comp is dual boot(xp and vista),and since I flash the bios-why I can't pass the bios screen.I have the first beep that everything is ok,so why he freeze.More opinions?
If I restart after I go in the windows it's ok.If I turn off the comp,and run it again it's ok.BUT,if the time is longer between two boots(say 4 or 5 hours),it will happen again.It's something with power.

 

Hi,

@ Goran.P Command Sergeant Major.
Tray with another power supply, could work.

 

Replace the battery to eliminate that as a possible cause. It may just be a defective one. The 4-5 hour gap would certainly suggest the CMOS not holding its settings.