Enabling all cores had the dual-core Core i5 661 matching the i5 750 however. This could be due to the clock speed advantage combined with Hyper-Threading support. The second set of MaxxPI² results shows the actual throughput that each processor was capable of. Using the WinRAR benchmark we measured performance using a single core and multi-core configurations. Oddly, with a single core in use WinRAR indicates that the Core i5 750 is faster than the Core i5 661, which we thought was unlikely to occur. The multi-core test also gives the Core i5 750 a serious performance advantage over the Core i5 661. On a positive note, the Core i5 661 was almost able to match the multi-core performance of the Phenom II X4 945.
