This is probably not the problem in your case, but it could be.

Set termination on. Set Termination Power off. There are three or four options for Term Power on the Seagate drives. Set it to Term PWR from SCSI bus.

The host computer should supply termination power. If you have more than one device supplying termination power, you sometimes end up with voltage level contention between the voltage regulators involved (which are set at slightly different levels) and then all kinds of wackiness and over-current drawing stuff happens.

Or so sayeth the Seagate Tech Support Guru I spoke to back in 1995 about my array of ST32550W drives.

Now, in most cases the settings for Term Power on the drive don't matter, because the host computer is supplying it, and a little extra doesn't always cause interference. But with my bunch of Seagate drives, it would not work properly until I stopped sending term. Power to the bus from the Seagate drives.

So, maybe you'll get lucky and this will be your experience too. It would be a simple fix.