I have two 80 GB Seagate ATA Barracuda IV drives that work nicely inside a BW G3, which ironically supplies their motors with a mere 7 volts.
Put either of them (one at a time with same cable as well as two other cables) inside a Sawtooth G4 (tried two of them, in fact) and at boot, the drive spins up, spins down, and the cycle repeats. The G4s are even supplying about 12 volts to the drive motors and the problem is present even if I try a drive while it is being powered by G3. It still powers up, then powers down and the cycle repeats.
Both G4s should have the latest 4.2.8 firmware and resetting the CUDA chip and pulling the battery has no effect, either.
It appears that at least the Sawtooh G4 is not compatible with this drive (or with the class of ATA IV drives)