Can't Extend fully to 1080p Monitor?

[Noobert]

Okay, so I have a Late 2008 iMac. I've had this setup before, but I moved my room around and needed a longer Video Cable.

I have a HP 2311x Monitor:
http://www.amazon.com/HP-2311x-23-Inch-LED-Monitor/dp/B004G8QO5C

The max it runs at is 1920x1080 @ 60Hz

so I ordered this 10 Ft VGA Cable:
http://www.amazon.com/gp/product/B0002AHT0M/ref=oh_details_o00_s00_i00

and the thing is, I have a Mini DVI - VGA Connector, which I have used before, but when I hook up this VGA cable, and use the correct settings, the HP Monitor is all messed up.

It doesn't extend to the full screen. The way it looks is, the left side of the screen, has a 1 Inch blank black spot, and the the right side had a 1 CM blank black spot. At first I thought maybe the wallpaper didn't extend, but what is actually happening is that, that's where my monitor thinks the end of the screen is.

So any advice would be greatly appreciated, cause I've never had this problem before.

Thanks

 

[flatfoot]

Try connecting it via DVI or HDMI.