We’ll compare the noisiness of the new Arctic coolers with that of the MSI Radeon HD 6950 Twin Frozr III Power Edition/OC and Gigabyte GeForce GTX 580 1.5GB SuperOverclock. You can view the results in this table as well as in the diagram below.
We can see that the maximum noise of the Arctic coolers is close to the minimum noise of the coolers from MSI and Gigabyte in 3D applications. Except for a small area of the diagram, the difference between the Twin Turbo II and Xtreme Plus II is negligible although the latter might be expected to be louder than the former due to the extra fan. The problem is that the massive plastic casing of the Twin Turbo II begins to resonate at a fan speed of 1200 RPM and higher whereas the Xtreme Plus II is free from that downside. Anyway, both coolers from Arctic Cooling are comfortable at speeds up to 1200 RPM and very quiet at speeds up to 1050-1100 RPM, which is enough to keep even a hottest and overclocked graphics card cool.
Arctic Cooling's Accelero Twin Turbo II and Xtreme Plus II coolers have only one downside. It's their high price. Even if your graphics card is as expensive as $300 and more, you may find the cost of these GPU coolers ($100 for the Xtreme Plus II or $66 for the Twin Turbo II) rather too steep. On the other hand, you won’t get such quiet cooling in both 2D and 3D modes with any original, let alone reference, cooler.
Besides the price factor, the fact that the hot air is not exhausted but remains within the system case can also be viewed as a downside, but this shouldn’t be a problem if your system case is well-ventilated.
Otherwise, the Accelero Twin Turbo II and Xtreme Plus II are blameless. They are highly efficient, quiet and compatible with a large range of graphics cards. They come with heatsinks, thermal grease and thermal glue included into the box and support PWM-based fan speed regulation. And all of this is capped by the 6-year warranty. Just a dream come true!