Total Systems Online...
Here's the lowdown. I haven't found any logic thus far.
1. Disassembled everything today.
2. Disconnected from wall outlet also as earlier.
3. Took out everything from cabinet except psu, ram, and motherboard.
4. Removed intel stock heatsink.
5. Applied Noctua thermal paste
6. Put the Noctua NH-D14 in place after trying alternate positions.
7. Kept only one fan on the heatsink and attached it to the "cpu_fan" socket on the mobo using y-spilt cable.
8. Booted up.
9. Heard those beeps finally.
10. This time after the usual, heard three meaning somethings not there. But it didn't shut down as earlier.
11. Unplugged and attached graphics card and booted up.
12. Same except there was display on screen. Last screen saying
"CPU Fan error!
Press F1 to resume"
13. Next, same setup but removed y-split cable, attached the one fan directly to "cpu_fan" socket.
14. Booted up to see last screen saying Boot device not found.
[Note: proves all thats left is hdds and y-split cable is at fault]
15. Had procured an exact y-split cable of Noctua from a benefactor. So put in both the fans of heatsink, attached it via y-split cable to "cpu_fan" socket.
16. Plugged in everything else.
17. Machine working fine. Flawless thus far.
[typing from this machine only]
Felling utterly blessed. Am indebted to all of you here. Very sorry for the delay. Will write more later. Need sleep right now.