The gigahertz only change from 3.5Ghz to 3.7Ghz so that doesnt seem like a big upgrade but we have too look at the other upgrades. You jump from 4 cores to 8 cores which is very useful for: gaming while streaming or doing something else, gaming in the close future generation (consoles are getting 8 cores so games are probably going to start using them well), multi core cpu rendering will be so much faster and overall you can multitask (useful when you have many monitors) so you can have google open with spotify and editing software and rendering software but your pc won't slow down like usually. You also jump from 2mb cache memory to 16mb cache memory which allows a faster connection between the overall computer and the CPU (It's like upgrading from an HDD to an SSD or upgrading from Slow DDR3 1333mhz ram to a lighting speed DDR4 4000mhz). You are also getting a much better heatsink which allows for overclocking (If you reaaally want to overclock then I recommend a watercooler). Only thing you lose is the onboard graphics but if you do heavy tasks like 3D rendering then you probably already have a dedicated GPU
This upgrade will make a big improvement from his AMD Athalon X4 950 to the AMD Ryzen 7 2700X this is because the system will have more gigabytes and a better processor
On your browser which should be a supported browser, you should log in to iCloud.com since iCloud is not supported on mac OS X earlier than mac OS X Lion 10.7.5
