XFX Radeon HD4670, no signal on monitor (stumped!)

Hey guys. I recently put together a new computer, and my situation with my graphics card has left me completely stumped at this point. I have a XFX Radeon HD4670 ( http://www.newegg.com/Product/Product.aspx?Item=N82E168... ) for my graphics card, and the MS-7525 ( http://h20000.www2.hp.com/bizsupport/TechSupport/Docume... ) for my motherboard. Also, my power supply is here: http://www.newegg.com/Product/Product.aspx?Item=N82E168...

My problem is that whenever I connect my monitor to my graphics card, the monitor will read "no signal". Also happens if I have the card in with the monitor plugged into the motherboard. The fan does indeed spin on the graphics card. I can only access the graphics if I take out the graphics card completely and use the onboard graphics. I have tried to disable the onboard graphics and changing my graphics settings in my bios to PCI-E rather than onboard or just PCI.
Also, if I turn the computer on with the graphics card in, not only will I get no signal, but I will not be able to turn off the computer with the power button.

Please help me out, I've struggled with this for a few days, and I was so excited to have my new computer ready for some gaming. Thanks.