PC wont bootup until after on for 10min

Here’s the syptoms: If i turn off the PC overnite, and try to turn it on in the morning… the power would come on..but the pc would not boot. it is not until after 10mins or so, after the pc is “warm”, and after hitting the power button off and then on, does the PC boot up with the ram counter (u all know the numbers that tell you how much ram you have)…. if i reboot the PC, it works fine, but it is after a long “off” time, that it is not working correctly.

I am wondering if any of you tech’s out there would know what it is, without me pulling apart everything from the motherboard to the harddrive to troubleshoot this.

Thanks