Getting 2nd HDD Caddy to work

I’m very surprised in your doggedness in making a sows ear into a silk purse ;-}

Keep in mind this is a very questionable system running Mojave given the limits in its physical RAM and the GPU it has. Also keep in mind this is the series which had the defective GPU so the systems lifespan is very questionable.

I personally would not make such an effort to keep it going since the Unibody systems that replaced it are so much better!

OK what to do to make this work:

Your optical drive is PATA not SATA and is an Ultra ATA/100 interface (running at ATA/66). This is very slow I/O speed! PATA is capable of data transfers speeds of 66/100/133 MBs/second, whereas SATA is capable of 150/300/600 MBs/second.

Here’s the correct carrier you need [produit lié absent ou désactivé : IF107-078] and you need a fixed SATA drive that runs at SATA I (1.5 Gb/s) so you’ll need to find a older drive as SATA II (3.0 Gb/s) or SATA III (6.0 Gb/s) drivers won’t work in your system reliably. Auto sense drives also won’t work these are drives that have circuitry to match the ports I/O speed.