120hz from gtx670 to plasma tv

[vvvuuunnnaaa]

Hello
I have issue with geting 120hz desktop on my panasonic plazma tv.
Was reading about more then 60hz on hdmi and found out that i need 1.4 cabel. Bought 1.4 and still 60hz is maximum. Im on fullhd 1920 resolution
Tv is tx-p42g30e
Gpu is asus gtx670 dc2
Driver is 391.24, there is few updates more on drivers but they lower gpu speed alot so this one are last working fine
Windows 7 64 sp1
Tv has 4x 1.4 hdmi

My question is: why is not going more then 60hz and if is posible , how to make it?
Thanks in front

 

[Glenwing]

There are no plasma TVs that support 120 Hz refresh rate.