Of course, I understand that temps play arguably most important part. Yet, would this not apply to case by case basis - excuse the pun? Gaming X trio seems to have the best temps but performing subpar which is a surprise, which leads to believe that performance deficit may be elsewhere.
Again, I must stress, I'm new to this so I'm new to being educated.
As regards to GN reviews, yes, I've seen that.
It's not just temps here though. It's the power limit. Your card will have a set power limit of about 330watts to 350 watts and it will draw what it can to achieve maximum boost clocks at a reasonable temperature. If it tries to draw say 360 watts, the card will lower clocks automatically as it isn't allowed to do this and you lose FPS.
Stock = 1700mhz, power required is 340 watts and temp = 60 degrees. No problem.
Straight overclock = 1800mhz, power required is 360 watts and temp = 65 degrees. Clocks reduced due to exceeding power limit
Voltage increase = 1900mhz, power required = 350 watts and temp = 80 degrees. Clock reduced due to temp
Undervolted overclock 1900mhz, power required = 340 watts and temp = 60 degrees. No problem.
Obviously the above is dependent on the card to determine the extent of the undervolt and associated overclock you can do but it gives you the idea. You're aiming to reach the limit of what the card can do whilst keeping it under the power limit and temps under control. You may get good results off an overclock and over voltage, but with 3xxx cards that's pretty much unheard due to their power draw.