I have thought about blogging a bit but there are already many people blogging who are much more knowledgable than me. :) This iMac is the 21" model, they have

I have thought about blogging a bit but there are already many people blogging who are much more knowledgable than me. :) This iMac is the 21" model, they have a smaller PSU and cooling, so the most powerful chip you can install is the i7-860s (82W CPU). I paid $25 from aliexpress. If you have the 27" iMac you can install the i7-860 (without s) that is a 95W CPU and can boost to higher clock speeds. This is also a more common chip so likely cheaper than the i7-860s. Both chips should boost the default max of 16GB RAM to 32GB RAM.