On my early 2008 3.2ghz Mac Pro, I found out for the first time, my third and forth hard drive bays are not showing up. Since new I have had two 1TB drives and wanted to add a third.

It should have been a five minute upgrade. However, I never got a drive to show up in the third and forth bays. I was able to format the new drive in the second bay and works fine in the second bay. The known working older drives would not show up in the third or forth bay.

Looking online, I did find that sometimes the logic board connection for the drive bays will come loose. I ended up talking the fan and shield off and made sure the connections were tight. I think I had the right ones! However, I did check all connections but had no luck. I did find lots of dust and I probably needed to clean it out anyway (processors had nice dust bunnies).

I am wondering if they ever worked and maybe something was never connected new? Is there something else to check?