What does this plug in to

[Charlie_3]

I've just bought the CIT Apache gaming case and its not working with my monitor. It says there's no HDMI signal. There is a mysterious cable on the case that says POWER and I can't figure out what it plugs into

 

[Mattios]

One of these?

Front panel connector - see your motherboard manual.

Regarding no signal, try this http://www.tomshardware.co.uk/forum/261145-31-perform-steps-posting-post-boot-video-problems