Monitor won't display after installing GTX 580

[J Jahans]

I've just taken out my ageing GTX 460 and put in a (also old-ish, but 100% working) GTX 580, but although my computer boots up just fine and I can hear the Windows sounds coming out of my speakers, there is nothing displaying on my monitor. I'm using a Corsair tx650w, which I've checked has enough power to run this card.

Here are the steps I took:
1. Uninstall 460 drivers
2. Power down, unplug everything
3. Unplug 460, replace with 580
4. Plug in everything again
5. Boot up

The weird thing is, although my monitor is completely blank when I unplugged the cable from the back of the GTX 580 my monitor started telling me there was no signal coming from my HDMI, but when I plugged it back in the message telling me there was no signal went away again but the monitor was completely blank still.

I can't see anything when I boot up either, no option to go into the BIOS or anything, and my motherboard has no integrated graphics. One of the big differences between this card and my old one is that it uses a mini-HDMI output, so I got a mini-HDMI to HDMI cable from Amazon, is it possible this is causing the problem?

It's been 4 years since I've done any major tinkering with a computer so it's very possible there's an obvious solution I've missed, any help would be greatly appreciated!

 

[clutchc]

If you're sure the card is good, the cable would be the first thing I'd consider, yes. Can you try the DVI connection?