Hard Drive from G5 into the Mac Pro?

I've upgraded from the G5 to the Mac Pro.

When I install the G5 hard drive into the Mac Pro tower, the Mac Pro makes a continuous buzzing noise. I screwed the G5 hard drive into the Mac Pro hard drive holding tray just like you would do with a Mac Pro hard drive. The Mac Pro hard drives are fine but the G5 hard drive make the continuous buzzing noise, making me think there is a compatibility issue.

Thanks for any feedback.

 

The G5 disk is a WD Caviar SE serial ATA hard drive from 2005.
Drive parameters: LBA 488397168. Model: WD2500JS-41MVB1.

This hard drive works fine in the G5 computer, but seemingly not so well in the Mac Pro, even though the screws fit snugly on the G5 hard disk within the Mac Pro computer. The problem is that I've already sold the G5 computer, and I would like to get some files from the G5 hard disk, so reformatting it from the Apple Partition Map type to GUID wouldn't help me in this situation. Although doing that may make this hard disk work better within the Mac Pro in terms of future use.

Here is a warning on the G5 hard disk label: Use either SATA Power or Legacy Power connector. Do not use both which may result in damage to the hard drive.
Does this mean that the G5 hard disk is "not" compatible with the Mac Pro?

Another thought I had was to try re-installing the G5 ATA hard drive again on the Mac Pro tower, and then try accessing it in safe mode. Not sure if that would make any difference to gaining access to the files and then transferring them over, and then reformatting the G5 disk to GUID.