Memory Bandwidth Performance
According to SiSoftware Sandra 2011, the dual-channel memory bandwidth of the new Intel Core i5 2500K and Core i7 2600K processors is comparable to that of the Core i5 750. As you can see the Core i5 655K is considerably slower with a bandwidth of 10.8GB/s, though keep in mind that this is just a dual-core processor with Hyper-Threading support.
The AIDA64 Extreme Edition results contradict those provided by Sandra 2011. Here the Intel Core i5 2500K and Core i7 2600K processors are considerably faster than the triple-channel DDR3 Core i7 975 Extreme Edition and Core i7 920 processors. Also, like the Clarkdale Core i5 655K, the new Sandy Bridge Core i5 2500K and Core i7 2600K processors provide a greater throughput when measuring write performance opposed to read performance.
Finally, we use AIDA64 Extreme Edition to look at L2 cache performance and right away it is evident that the Intel Core i7 2600K and Core i5 2500K provide considerable improvements. The write performance was higher than the read performance of the Intel Core i7 975 Extreme Edition while the write performance was twice as strong.