It's nice that you have instructions, but where do I find the parts? My volume up button stopped working after it got a little wet. Is that a tell for Apple that it had moisture exposure?

How about the headband? Is it replaceable? Or maybe the ear cup tip?

I just installed a Seagate ST3000DM001, and I have the fast fan issue, so I took it all part again, and checked for another connector for the drive, and there are none not being used. I put everything back together, and did an SMC reset, and it's still running fast.

1) What could be missing? The existing drive was a Seagate ST31000528AS, and had no extra temperature sensors on it, and no other wiring.

2) Is it the drive? Is it incompatible in some way?

While having it open again, I checked for any other connections that might have been removed, or loosened, and found none. I guess it's not hurting anything running fast, but it would be nice to figure out what's causing it. Thanks!

Yeah, the old Mac Pro is a hernia inducing item, and a back breaker too.

The connectors for the two video cards aren't the same. I doubt that one could put two SSD video cards. Sad, but that's why the Thunderbolt.

Looking at the round IO card, it looks like the two connectors for the video cards are different so I seriously doubt that one could swap in a second SSD capable video card to get more SSD storage.