One of my rigs went offline and I wasn't able to get it to power on again. Long story short: I've ordered a new MB to see if the prob was my old one. After disconnecting all the gpus (5x Sapphire Nitro+ rx480), I noticed ALL of them have some small amount of this oily residue that seems to originate from around the pcb near where the heatsink pipes run (see pics). The oil/grease is clear, and doesn't have a smell I can detect. I'm guessing its thermal grease (from google searches), but I've never had this happen! These particular cards haven't been running long (~4 months I'd guess), and haven't gone over ~80 degrees as far as I've seen.
Should I be worried? Should I/how to clean them up? I'm assuming this has nothing to do with my rig issue (I hope!).