Looking for a suggestion.

[Suriya Bond R]

What will happen if I pour a "LIQUID NITROGEN" into the water cooling tank? Is it work fine?

 

[digitaldoc]

It would be too cold, and damage the pump. You could also freeze any residual water in the tubing, which would hamper the cooling. I have worked with the stuff in a lab, and it is damn cold, with frostbite as a constant safety concern even with protective gear.

Good idea for a Youtube video, but lousy idea to cool a PC for routine use.

https://www.youtube.com/watch?v=ZF8S3Nn7mTQ

As you can see, the N2 gets poured directly onto the CPU, and not circulated with a pump.