Itai Tavor writes: "Last week I installed the new PCI SCSI JackHammer control panel version 1.3 (for the PCI SCSI JackHammer card). On the next cold restart after the control panel updated the card's driver, and on every cold restart since then, the hard disk does not spin up at all. The only way to get the drive to spin up is to boot from another drive, then run Apple's Drive Setup. When Drive Setup queries the SCSI bus the drive starts spinning up, and after that works with no problems until the next cold restart."
Update: Two JackHammer users report never having had this problem.