I did not find any reviews or benchmarks, but gainward typically is an aright brand, if not ever so slightly cheap. If it is the stock cooler, don't even worry about it, as all reference coolers no matter the branding on them, are pretty much the same.
The phantom variant is a great cooler, but is rather large and slightly louder than msi twin frozr, asus direct cuii, or evga acx coolers. If you can find one of these for cheap, go with them over the gainward phantom or reference variants. The msi variant specifically can usually be found for a great price with a little searching online.