Concerning the GPU not going to 2D clocks in desktop with 120hz, it depends on which monitor you have.
With my current Viewsonic 120Hz monitor the GPU memory always runs at full speed which puts up idle temps quite a lot. But with the exact same GPU and PC with the BenQ 120Hz one, the GPU went to 2D clocks with no problem.
Concerning which monitor is best etc, its completely down to personal taste. I have owned the benQ and viewsonic together and even though a lot of people praised the benQ as the best gaming monitor on the market, and even though the model I got had no backlight bleed, I still preferred the Viewsonic. The BenQ has very strong overdrive settings, and you cant put them to "medium" - its either fully on, or fully off. When its completely off then the monitor performed worse than my Samsung T200 2ms 60Hz monitor. Also tests showed the input lag was very low on the BenQ, the lowest there is apparently, but having played on the viewsonic as well I disagree and feel the viewsonic has even better input lag. There was also this weird case where I felt the BenQ was not always running at 120Hz and that the refresh rate was unstable and would dip, even if just by 1Hz. I noticed this because, with every other monitor I have owned, setting the framerate limit of a game to be identical to the refresh rate gave smooth results, albeit with some screen tearing. However with the BenQ, I couldnt get it to be smooth, and there was still screen tearing. And the default colours were awful, Im glad there were reviews out there that cared about colours enough to tell me which settings to use as that improved the colours 100%.
Thats when I made a striking discovery! Gamers dont know what they are talking about. These pro gamers have no clue as to what a smooth game is or how to best optimize the setup for optimal gaming pleasure. So never follow their advice. I mean on the BenQ there is even a "gaming" setting which, when selected, makes everything blurry and bright. I feel sorry for the gamers out there with that monitor that endure games with that setting thinking its the best way to play the game, as designed by the almighty cs1.6 player spawn and heaton.