1. POST (Power On Self Test, i.e. BIOS screen) comes 1st, then booting. They are not the same.
2. POST requires a keyboard, CPU w/fan, 1 RAM stick, graphics (onboard or card), nothing else.
3. Fans & HDD spinning means little, except +12V power is available.
4. If you hear 1 beep, it's POSTing.
5. Asus doesn't list M4A88T as a valid model number. There's more letters/numbers at the end.