Hdmi cable from computer to TV yields NO SIGNAL. Help!!

Hello everyone. Today I unpacked my HDMI to HDMI cable and recently gave up trying to get it to work.
I've plugged the cable into the back of the computer where it says "HDMI" (simple enough) and tried ALL HDMI-in ports (is port the correct word?) on 2 different TVs, one being a LCD and the other a Plasma.

So far it has ONLY been showing "No signal" on the TV.

The Nvidia Panel doesn't identify another monitor, and thus won't let me click to make the TV the "priority screen".
I've tried right clicking on desktop and going into preferences and display-settings there to identify the monitor but that doesn't work either.
Tried restarting my computer, restarting the TV, doing it in different orders and so on. NO results.

My drivers for my GTX 580 are the latest.

RIG:
GTX 580
i7 2600K
ASUS p8Z68 v-pro
8 gig RAM

Sorry for any misspelling and whatnot.
Thanks in advance!

Are you plugging it into the video card? AFAIK, the video card does not have a regular HDMI output, but rather a mini-HDMI output.

Well, I'm not sure. To be honest, I might as well be plugging it into the motherboard.

What is this mini-HDMI-output you speak of?

I can't find it at the back of the computer.

After VERY little searchwork, I saw this plastic thing covering an output. I pulled it out and sure enough, it's some sort of output, BUT it doesn't say what kind of output it is.

This output is directly into the gtx 580.

So I suppose I need some other kind of cables for this then, right?

After VERY little searchwork, I saw this plastic thing covering an output. I pulled it out and sure enough, it's some sort of output, BUT it doesn't say what kind of output it is.

This output is directly into the gtx 580.

So I suppose I need some other kind of cables for this then, right?

Heavygunned

Yep, a mini-HDMI to HDMI adapter, in fact. If you're lucky, your video card would have come with one. If it didn't, chances are it may have come with a DVI to HDMI adapter. But if none of those were included with your card, you're going to need to either purchase a DVI to HDMI adapter, a mini-HDMI to HDMI adapter, or a DVI to HDMI cable/mini-HDMI to HDMI cable.

So I searched through the box and found this Mini-HDMI to Hdmi cable (One end tiny and the other end normal sized). However, the cable only measures 2 metres, and I need about 4,5 to reach my monitor.

I guess there are solutions to this, and longer cables?

Yeah, conclusion is I'll just have to buy an adapter.

Thanks for your replies mate!