either way though i'd probably return it. i would pay attention to where a card was located when i was looking to get one and many coastal areas, mainly southern coastal areas..
the one i wound up with came from arizona. I've also heard of idiot miners using window AC units with their equipment, i could see something like this happening in that case
or some kind of slight chem spill on it, ALU does not rust. that could be nickel coated copper, with what ever spilled on it(if it did) would be causing that. now if like the other two said above i agree about that, with it being in a 24/7 AC room with other mining cards. i could see that accelerating rusting. I am still leading with some kind of chem spill on the nickel finish eating it off and causing the copper to rust.
I am 50/50 on it, could test it out and see how it works. if your really that worried, just return it.
yea its not all aluminum, there are steel parts on top of the fin stack for the fans and shroud to screw to.
When i saw this i magnet tested my evga 3070Ti fresh from rma, i had to take the shroud off any way to get it back in the little case
any way the magnet sticks, its probably better this way, that steel is less likely to strip out when installing the fans and shrouds on the assembly line
thats rust right under the shroud for sure. i still think it should just be sent back. do you have a link to the listing on ebay?