I bought an MSI R9 280X last Christmas and decided to take it out for some case cleaning (Carbide 300R), to my surprise when I turned it over on the cooler side there was some sort of oily liquid on the shroud. Decided to have a closer look and I saw some residue on the cooler fins too, can someone shed some light on where this mystery oil could've originated from? My PC is completely air cooled btw. I cleaned the stains off the shroud but I can't get to the the stains on the fins themselves.
Most likely came from the bearing in one or your video cards fans. Time to RMA the card. You should still have warranty on it. It's not a common issue, but I have read about this happening from time to time.
Just webmailed OcUK about the issue and the CS response basically mirrored sincreator's. They said that the oil was probably excess from the fan assembly and this tends to leak out when the fans spin at high RPM, which makes sense because the splatter profile was a semi-arc around the fans themselves and they also said that the leakage will not be detrimental to my GPU's performance in any way, shape, or form. I'm not losing sleep over this right now but I see my future self having to make very colourful warranty claims to MSI when a fan flies off the bearing and ninja-shreds my PC, here's hoping that does not happen.