Method Am I doing partial hanging wrong?

[Lambybahhhhhh]

First off Im using a power cord, every time I tried it out I would feel pressure in my head and my hearing slowly fading. My anchor point is a wooden pole in my wardrobe. I tie the cord around the middle or base of the neck, as I've heard that's the most effective/painless. The knot is directly on the back of my neck and I lay down letting my head rest. I've tried about 4 times already what am I doing wrong?

 

[Shadows From Hell]

I'm gonna guess a power cord isn't a good option, as it wouldn't tighten as good as a rope. A cord will only get so tight before it becomes useless.