Are you sure it's the fan that failed? It could be a more severe issue in the motherboard so that it no longer provides power for the fan. Usually motherboard speaker and/or led can tell if it's a cpu fan failure. And.. Noctua isn't a no-brand manufacturer, it probably makes the best fans of them all. Also.. replacing the fan of the stock heatsink is pointless, you might as well buy an aftermarket heatsink such as Coolermaster Hyper 212 or Corsair Hydro series.
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