Corsair uses Shin Etsu which is top notch stuff. I am not certain what NZXT uses though.
Well, As JediYoda or somebody said, "This subject has been rehashed so many times." And I'm here to promote the snake-oil of nano-diamond and Liquid Pro, like I always do with these posts.
I was able to re-use the IC Diamond paste three times for changing CPUs and remounting heatsinks, knowing that it would serve just as well as it had with the fresh application.
But think of it!! The Kraken X61 pushes the envelope for AiO coolers, or so the rumors abound. If you can exceed an "un-enhanced" heatpipe cooler by 6 to 10C, that's good. And for these new processors -- essential.
It's essential because heat transfer depends on the areal size of contact. Fewer square millimeters? Less heat wattage transferred per unit time to the heat-exchanger surface or waterblock. And with the smaller lithography and the die shrink, the area of contact has shrunk. It appears that even with the voltage decreases of new processor lines to which the die-shrink contributes, it isn't sufficient to compensate for the limited ability of heatpipe technology to adequately transfer heat from the smaller die.
[Since I'm not an expert, speak up if I'm essentially wrong about this.]
Ordinarily, if quantum physics didn't seem to be getting in the way, we'd think that the lower voltage and even spec TDP decreases would eliminate this problem and make it possible for higher clocks, but it hasn't -- yet.
Instead, instruction-set additions and design improvements make up for speed in sheer Ghz/Mhz. But we're still talking about the health of the same basic material -- silicon.
So I would think that again we're in a deeper pit even with AiO coolers. Unless somebody comes up with some weird
positronic framistanic discomboobulator innovation in coolers that don't have a radiator separate from the main point of processor contact, liquid cooling is the wave of the future for anyone who tweaks their systems to higher speeds that are more than just casual, modest flirtations with the BIOS settings.
Even so, at this point and possibly challenged by the Kraken and models that have yet to appear, you can get a heatpipe cooler to match good AiO coolers.
And the problem with the AiO makers: their solutions have to fit into a variety of cases to capture more market share. So the radiator size on AiO coolers will be the limiting factor, in addition to using only a single pump and no reservoir.