Adobe Photoshop is optimized for multiple-core CPUs but not all of its operations and filters can benefit from as many cores as possible. Therefore the six-core CPU does not enjoy an overwhelming advantage. Besides the two extra cores, the increased L3 cache contributes greatly to its result.
Video encoding is a task that can be easily paralleled to multiple CPU cores. The six-core Core i7-980X is over 40% faster than the four-core Core i7-975!
We’ve got the same picture at high-definition video editing in Premier Pro.
WinRAR can make good use of multiple CPU cores, too, but the performance benefits from a fourth core and more are really negligible. That’s why the Core i7-980X and Core i7-975 are similar in this test. The six-core processor’s 12MB L3 cache is not very efficient as the effect from its large capacity is negated by its high latency.
Excel 2007 can parallel its mathematics well enough. The test task is solved much faster on the newer CPU.
The software audio studio Sonar 8 Producer runs faster on the six-core CPU when mixing tracks. The Core i7-980X is about 5% better than the Core i7-975.
Final rendering is the type of load that eagerly reacts to any extra CPU core available. The 20% advantage of the Core i7-980X over its opponent is an expected result.
I will also check the CPUs out under single-threaded load by benchmarking them in the computing test MaxxPi and the chess program Fritz, in which I manually set the number of CPU cores at 1. These tests is interesting because senior CPU models in the Core i7 series feature Turbo Boost technology which can increase their clock rate to 3.6 GHz when only one core is in use.
As you can see, the Core i7-980X and Core i7-975 are roughly similar in these tests, the older CPU enjoying some advantage due to faster cache memory. The Core i7-870 comes closer to the leaders, being mostly limited by its lower memory bandwidth.