Both models
i3-2120 and
i7-3930K are based on
Sandy Bridge architecture.
"Sandy Bridge codename was originally ""Gesher"". The development began in 2005 and four years later, the first Sandy Bridge CPU was presented. The most prominent features are Intel Turbo Boost 2.0, AES encryption and SHA-1 hashing acceleration, Advanced Vector Extensions (AVX) 256-bit instruction set and the ability to have up to 8 physical cores or 16 logical cores through Hyper-Threading."
Using the multithread performance as a reference, the i3-2120 gets a score of
53.5 k points while the i7-3930K gets
155.9 k points.
Summarizing, the
i7-3930K is
2.9 times faster than the
i3-2120 . To get a proper comparison between both models, take a look to the data shown below.