Issues after installing XFX 7950 and new ram

[Malckeor]

I put my new XFX 7950 and 16GB of G. Skill Ripjaws X into my computer today. However, I ran into some issues. When I boot the computer up, it turns on for a few seconds, then turns off, then turns back on and the monitor tells me to check the signal cable. I tried putting in my old ram and graphics card and then booting it up, but I'm still getting the same issue.

I have an anti-static wrist band so I don't believe I damaged anything. How do I fix this? Here's my specs:

XFX 7950 3GB (replacing a Sapphire 6950 2GB)
G. Skill Ripjaws X 16GB DDR3 1600 ram (replacing a 4GB G. Skill Ripjaws)
OCZ Vertex 3 SSD
ASUS P8Z68-V Pro motherboard

I uninstalled my 6950's driver via the device manager before installing the new parts. I have no idea what could have gone wrong, especially considering I have an anti-static wrist strap.

Also as a sidenote: I dusted my computer a bit when I was inside of it, and maybe I could have hit something? I don't know.

[glo]

1. Put your old RAM in and see if it works, if so, go stick by stick one after another on your new set and see which one is bad.

(If that doesn't fix the issue)

2. Put your old GPU in with your new RAM and see if it works.

[Malckeor]

I fixed it. It was something really, really stupid that I feel too embarrassed to explain.

Thanks anyway.

[vesseblah]

Forgot to plug in PCIe power cables into graphics card?

It's always good idea to post even stupid things like that here because it's a) so common mistake and b) people googling for help will find the solution also in this thread.