SSD installed on 6th internal SATA port, Mac Pro (July 2010) 12-core
When I received the machine, I cracked the case open immediately and discovered that the 5th and 6th SATA ports were still on the motherboard, easily accessible.
5th and 6th SATA ports are on the motherboard at the front of the Mac Pro (July 2010) 12-core
5th and 6th SATA ports are on the motherboard at the front of the Mac Pro (July 2010) 12-core. By default, one is connected to the SuperDrive.
However, unlike older Mac Pros, the new Mac Pro uses SATA for its optical drive (instead of PATA), so one of the two extra SATA ports is being used. Luckily, Apple wired up both SATA ports to the optical bay, so adding a 6th SATA drive the Mac Pro is as easy as plugging it in. For a spinning disk you'd need some sort of tray to lock it in place, but an SSD can just be left hanging. In the photos, you can see a heat sync attached to my SSD; this is something that came with an old Mac Pro SSD tray adapter -- I decided to leave it on the drive.
Mac Pro (July 2010) 12-core with optical bay pulled out
Built-in SATA + power connector makes it easy to install a 6th drive in Mac Pro (July 2010) 12-core
So now, I have 5 internal drives in my new Mac Pro, but I'd really like to have 6. I am evaluating the following options:
1. Remove SuperDrive and use it externally. I have an external, bootable SuperDrive enclosure (USB / Firewire), so this would be easy. I almost never use the optical drive, so this is a good option (I don't care if it's slow). I'd mount the two 2.5" SSDs using a [2.5 to 5.25 bay adapter](http://www.xpcgear.com/scythe-2-5-to-5-25-bay-rafter.html).
2. Add the 6th drive via eSata (though Sonnet Tempo E4P PCIe card). The Mac doesn't recognize eSata drives attached to the Sonnet card until boot (not bootable), and since I would be using the 6th drive for swap, I'm not sure if this would work.
I'm leaning towards option 1.
Incidentally, I ordered the 12-core machine with a 1TB drive pre-configured. The drive they shipped is a Western Digital Caviar Black 1TB (WD1001FALS-41Y6A0). This information can be hard to get, so I'm putting it in this post.