speed and length
#11
NBZ hasn't been around for ~ 6 months. But IIRC what he ended up doing was upgrading the radiator and adding two larger fans to the GPU. Then he had to set the clock to 1000 Mhz and Powertune to 0% or -10%. Would probably be better to do full watercooling instead of that hybrid cooler crap. But even then you have to deal with the fact that it is a 500W card, and it really doesn't like pulling that much. So even if you get the heat under control you'll still won't be able to overclock and will also probably still have to set Powertune somewhere between -10 and 0.
#12
it's all in the wrong direction goes.
clearly not the case in the temperature of something
speed first GPU is falling at the first start of HC
until the moment when the card is not loaded and was about 100% Cold
#13
Again, it's not just about temperature. It's also about how much power the card is drawing. That's why it's called Powertune. The firmware on the GPU will not allow the card to draw more watts than it thinks it can handle. If it starts to draw too many watts, it will throttle the card. The 290X draws ~300W, and you have two of those chips on your card. But your card is only spec'd for 500W. Surely you can see how that is problematic. And you are overclocking, which is only exacerbating the problem.

Drop your clocks down to at least 1000 Mhz, if not 975 Mhz. Then start adjusting Powertune, starting with 0 and decrease it until the card doesn't throttle as much or as often.