I am talking about the Polycarbonate Mac Mini 2006 to 2010 version, aka the CoreDuo/Core2Duo series. There are two main variants: A1176 and A1283 models. Much of the case and electronics of these two are the same, with the exception of the CPUs and Firmware on the machine. These Mac minis can be acquired on sits like Ebay for under $50 and in many cases around $25. The 2011 to 2021 Mac Minis use the “i-Core” Intel CPUs, and many of them can also be upgraded with a simple CPU Swap like from i3 CPU to i7 CPU but there are some issues with cooling which also needed to be upgraded.
 
A Basic Upgrade of the A1176 Mac Minis are to replace the CoreDuo CPU with a Core2Duo CPU – the T7200 CPU, which will push the Mac Mini to 2.0GHz and with a firmware update (“MacMini Firmware 2.1”) allow it to have 3GB of RAM. 4GB of RAM can be installed but only 3GB will be seen.
 
The A1283 Mac Mini already has a Core2Duo CPU, but they can be upgraded with a faster CPU, taking the Mac Mini from 2.0GHz to 2.66 with an Intel P8800 Core2Duo CPU. No Firmware update is needed as all A1283 Mac Mini have the same firmware.
 
In both cases, Faster RAM and a Fast SSD would bring performance improvements. With the SSD, the system would run a bit cooler as the SSD does not generate heat like a hard drive with spinning platters would.
 
Swapping CPUs on CoreDuo systems seem to also work on PCs and PC Laptops, as per the Youtuber “Alan and Cat” who does laptop and PC repairs and upgrades. The question is if there is a Core2Quad CPU for Laptops, can it be used to further upgrade the laptops and Mac Minis? Such an upgrade would put the system from a Dual Core CPU to a Quad Core CPU. There would be issues with cooling but that can be dealt with. The Core2Duo to Core2Quad upgrade is possible on Desktop CPUs. But the question lies if there is a “Mobile” version of the Core2Quad CPU. If so, then such upgrades are possible.
 
A lot more research is needed to see if this is even possible, and to what extent. But as is, older Mac Minis can be updated with a T7600 Core2Duo CPU at 2.5GHz with a Firmware Update and the 2009 Mac Minis can be upgraded to 2.66GHz with P8800 Core2Duo CPU. Faster RAM and a fast SSD can also improve the performance of these machines.