What the? No they are not. Source: any review.
With the grand exception of the EVGA EE series, which Carebear (and I) have. They use a radial fan (not even reference 460 uses one) and many of them came with a crappy application of thermal paste resulting in high temps and loads of noise. You can lower it some by re-seating but in the end it's still a radial-fan design and it's not designed with high OC's in mind either.