LG29UM65 Monitor

I purchased this monitor - http://www.newegg.com/Product/Product.aspx?Item=N82E16824005624

and hooked it up via DVI - I was told I wasn't getting true 2560 X 1080 with that connection due to Asus MOBO p8z77-v only able to support 1920 X 1080 with that connection, but could get it with a DP cable.

I bought a DP cable, but the resolution seems the same.

If I go to Screen Resolution, it says I am getting that Resolution with either cable.:confused

Any suggestions?

Thanks,

Paul

Comp Specs:

Computer type PC/Desktop
System Manufacturer/Model Number Self-Built
OS Windows 7 Professional X64
CPU Core i7 (2nd gen) i7-2600K / 3.40GHz
Motherboard ASUS P8Z77-V Intel 7 Series Motherboard
Memory DDR3 2400MHz (OC) 16gb
Graphics Card Intel(R) HD Graphics 3000, -1988 Mb
Sound Card 8 ChannelsAudio Chipset Realtek ALC892
Monitor(s) Displays LG 29UM65 Black 29"
Screen Resolution 2560 x 1080