The
G645 is based on
Sandy Bridge architecture while the
X5670 is based on
Westmere.
Using the multithread performance as a reference, the G645 gets a score of
35.4 k points while the X5670 gets
115.4 k points.
Summarizing, the
X5670 is
3.3 times faster than the
G645 . To get a proper comparison between both models, take a look to the data shown below.