Toshiba Satellite L300 PSLB0A-08L022 can't boot.

Hello, I have Toshiba Satellite L300 PSLB0A-08L022 (Australian version), problem started few weeks back and i have been trying to resolve it since then but no luck.

ISSUE:
Laptop boots fine, POST fine, but can't boot into windows, it just shuts down and restarts automatically and this thing keeps repeating.

MEASURES:
Changed hard drive = no luck
Changed RAMS = no luck
Tried Windows Setup without hard drive = no luck
Tried reinstalling Windows 7 and Windows 8 = restarts at "windows loading files"
Cleaned the processor grill and fan and reapplied thermal paste = no luck
Turned off all features from bios and set Hard drive to "compatibility mode"=no luck.
Tried disconnecting wifi and modem cards = no luck.

However when i booted it to portable windows xp through Hiren's boot cd it did boot up and that windows was working fine, i took it as advantage and i updated my bios too but still NO LUCK.

Now its like just heavy paper weight, it Post fine, but it get restarted when trying to boot in windows or reinstalling it, but it does get into SAFE MODE correctly. Any help would be deeply appreciated.