I have an ASUS P4PE. I am attempting, without success, to make a
Seagate SATA drive work with it. The drive is new and is properly
cabled, both power and data.

I have four other drives in the computer: three hard drives and a
CD-RW. All are regular old IDE/ATA drives. Am I limited to a
maximum of four devices?

I would upgrade the Promise BIOS, but I cannot figure out which BIOS I
want. It appears the 376 BIOS (which I think applies here) is the
same as the TX4000?

I'm not sure what difference upgrading the Promise BIOS would make. I
have flashed the motherboard BIOS. On a DOS boot, FDISK still does
not recognize the drive.

Seagate's SeaTools Desktop Diagnostic does not find any sign of a SATA
drive in this computer.