How do I add a second drive in my system?

Your optical drive bay uses a PATA interface Vs SATA. So you’ll need a special carrier which converts the signals. Here’s the needed part: [linked product missing or disabled: IF107-078] and here’s the IFIXIT guide you’ll need to follow: Installing MacBook Core 2 Duo Dual Hard Drive.

Now the tricky part! Keep in mind the PATA connection is much slower than your SATA HD connection. So if you are planning on installing a SSD drive then you’ll want to place the SSD in the HD’s current location to gain the full ability of the connection.

But! Your systems SATA port is only SATA I (1.5 Gb/s) for the first generation and SATA II (3.0 Gb/s) on the last of the A1181 models.

So you do need to make sure the SSD (or even HDD) is able to match up with these older SATA specs. Most of todays drives are fixed speed SATA III (6.0 Gb/s), that is only able to run at the given speed they were designed to run at so these drives won’t work in your system.

Some drives have auto sense logic which allows them to match the I/O speed with the system its fitted in. The only way to know is to look at the given drives spec sheet to see if multiple SATA speeds are listed. As an example this SSD has this ability: Samsung 860 EVO SSD

Moving the HDD also has its risks! Unlike the HD SATA port the optical drive port does not offer crash guard protection. So you will need to be extra careful when moving your system when the system is on as the HD’s drives head could be in the middle of the drive reading or writing and if you give it a good bang could damage the drive. So make sure you have a good backup of your stuff and keep it backed up just in case.