I have a working Vista 64bit PC to which I added a second SATA disk. The BIOS sees the disk and is set to auto set its parameters. I boot the PC but the disk is not visible to Vista. However, if I let the PC sleep, then when it is awakened, the disk is there and able to be formatted with NTFS default clustersize. I can then write files to the disk and all is well. Until I reboot. Then the disk is visible to BIOS but not Vista until it is time to wake up from sleep.