[SOLVED] PC not booting when external HDD is connected ?

[ebosss03]

Pc wasn't booting today, not even getting to the bios. I unplugged my external HDD and the PC booted okay. How can an external HDD brick your entire system?
It quite amazed me that it wasn't even showing BIOS just a black screen.

 

[USAFRet]

During start up, the system checks every connected drive.
If one of them is faulty, that can affect the boot process.