Factory Reset a Apple Mac Pro A1186

Three Mac Pro models used A1186 per Mac Tracker, topping out at either OS X 10.7 or OS X 10.11.

Versions of OS X which won’t be all that useful, if you want to connect to anything.

Including connecting to the Apple Recovery servers, which don’t support booting Macs this far back.

To boot from the DVD here, insert the DVD into the drive, press the power button, and then press and hold the Option / Alt key immediately on power-on, and continue to hold the key until the startup choices appear.

A1186 includes Mac Pro 2006 through 2008 models.

Internet Recovery is NOT available in ROM in most Macs before 2011 models. So you will need to explore this list of other possibilities.

When your computer was released, the way you launched the required Utilities (including Disk Utility and Installer) was to use the ones on the Release software DVD. if you have a model-specific version for your specific model (unlikely) or a Full Retail 10.6 DVD —and a graphic card supported by early 10.6 — you use the Utilities on the DVD, boot and install that version, then use Software update to get to 10.6.8 with all updates, which is the first version that can reach out to Apple servers and download and install a later version.

If you have replaced the graphics card, so that it is one that does NOT have Drivers included in the release DVD, you can boot the release DVD, but you get no picture. if you have the old card lying around, you could re-install the old card to use the Installer DVD.

10.11 El Capitan is a recommended waypoint, even if you expect to install a later version. 10.11 allows encrypted Internet connections and Mac App Store access. That makes getting later versions much easier.

Welcome!

I do have the OEM 10.8.6 Apple DVD for installation.

Do you mean 10.6.8? macOS 10.8 never made it past 10.8.5.

If it is not the system restore disk the came with the computer, your disk must be a full retail install disk as pictured. Gray disks the shipped with a different Mac fail to work. Copies burned to disks often fail as well.