120 hz limit on 240 hz monitor

[kamberivan]

Hello guys !
I have problem with my new monitor alienware 2518hf 240 hz. My grapich card is sapphire hd 7970 vapor x.
When am trying to put 240 hz on windows, its showing me only 120hz max. Please can you help me i connect with hdmi cabel.
Lots of people says that problem is with hdmi cabel and i need get display port cabel?

 

[Glenwing]

The Radeon 7970 has HDMI 1.4 which is not capable of 1080p 240 Hz. You need to use DisplayPort.

 

[kamberivan]

I buy display port cabel, everything is working now, thank you !!