I gamed a ton mostly with headphones on, so the noise was only bad on the rare times I was using speakers. I eventually replaced that 5850 with a used 6870. Performance was fine but it had a hard coded undervolt that would BSoD when watching YouTube or video while being completely fine in-game. I'm sure it's why the owner sold it. I couldn't force the GPU BIOS to alter the voltage (and boy did I try), but ATI Tool fixed the problem through software. Only issue with that was it made Steam overlay stop working, so I'd miss messages from friends.
Funny enough I had a similar issue with an NVidia 5900XT, where I had to edit the BIOS file with 3.5 floppy disks. Last NVidia card I had until a 680 almost a decade later.
None of this had to do with replacing GPU fans, of course.