Are you sure the ratting is coming from the fans and not the pump block/motor housing? As per the leaflet int eh AIO cooler, it's best advised that you contact Corsair and notify them of the issue and see if the fans or even if the AIO itself needs replacing(and subsequently see if the bundled fans fall under warranty).
Provided the fans are at fault+Corsair come back suggest a replacement, you're fine. On the other hand, once you get a definitive answer that the fans aren't covered under their warranty scheme, you can buy fans from the likes of Scythe, Noctua, Bitfenix, EKWB...the reason this list looks more like fans for watercooling, is because you're dealing with a radiator and the Corsair radiators have notoriously high FPI's...