And while you are at it, take the time to upgrade the hard disk (a 2.5″ SATA drive) to an SSD, preferably 128GB or more. The machine can only use around 3.3 GB out of the total of 4GB that is recognized, due to limitations of the 32-bit processor. If it still doesn’t work, try to do a PRAM reset. If the machine doesn’t boot up or doesn’t recognize the extra RAM, check that the memory modules have been securely inserted.After a reboot, the Mac Mini should recognize 4GB of RAM.Simply turn the Mac Mini off by pressing the Power button, and turn it back on You may see some distorted pictures on the screen, which is normal. At this point the firmware upgrade is completed.Wait for a few seconds and press the power button until the power LED flashes.Turn off the computer by shutting it down from the Apple menu.Sudo bless-mount /-firmware/System/Library/CoreServices/Firmware \ Updates/EFIUpdaterApp.efi-payload/System/Library/CoreServices/Firmware \ Updates/LOCKED_MM11_0055_08B.fd-options “-x-apple-efi payload0-data” -verbose Check the permissions of the files, or just do a chmod 777 on the files to be safe.
A detailed step-by-step guide on how to upgrade the processor can be found here. Compatible processors can be found on eBay for as low as US$20 and available at a wide variety of speeds – 2GHz, 2.16GHz or 2.33GHz.
Although it is possible to patch the installer to run on a Core Duo, I would still recommend upgrading for a straightforward installation experience.
Mac Mini 2006 comes with a Core Solo or a Duo Core processor, whereas Mac OS X Mountain Lion requires at least a Core 2 Duo, so you will need to upgrade the processor on your Mac Mini first before continuing. Although I have not tested it myself, the same steps would probably work if you have an early-2006 Mac Mini. This tutorial shows you how to get Mac OS X 10.8.4 (Mountain Lion) running on a late-2006 Mac Mini (model A1176), which officially can only support up to Mac OS 10.6.8 (Snow Leopard), according to this Wikipedia article.