wPrime 1024M
Wprime is one of the few well-known Pi calculators that uses more than one thread (both SuperPi and Hexus PiFast only use one thread). As you can see, the overclocked i5-3570K @4.5 GHz barely surpasses the i7-3770K on stock frequency.
Hexus PiFast
Hexus PiFast is a single-thread Pi calculation software, which makes Hyper-Threading useless while running it. The results confirm that, since the i5-3570K beat the i7-3770K @ 4.5 GHz.