I will look around for 7020 or 9020 mt with i5 cpu this swap worked for me previously with sff model and no issues until now ...
Hi Guys Looking for some good advice, regarding heat sink. I have eye on Dell Optiplex 3020 MT i3 4150 3.5Ghz but I am not sure if that heat sink will be ok to work with intel i7 4790  My concern is it might overheat under gaming stress   
Dell Optiplex 3020 MT i3 4150 3.5Ghz CPU upgrade \ heatsink