1 vs 2 vs 4 Core
Here in a nutshell are results obtained in tests with Core 2, with one core (by using a E6700 with only one core activated), two cores (E6700) and four (QX6700). The 100% correspond to performances with one single core:
Increasing from 1 to 2 cores improves performances with 3ds, Maya and TMPGEnc: 94, 97 and 85%, respectively. Increasing from two to four cores, however, is less interesting, because performance improvements are still very good with 3ds and Maya (+90 and 96%), while they are only 47.3% with TMPGEnc. Performances with Mathematica and DiVX 6.4 are increased by approximately 20% with the Quad Core, 4% with WinRAR and 1.6% with Far Cry.
Does the problem come from the processor or application?
FSB1066 vs FSB1333
Some believe that the performances of the Quad Core would be restricted by FSB and this would explain the smaller improvements. This is an interesting point considering that the two dies share the same FSB and that communication between the dies and cache management also needs to use the FSB.
To find the answer to the previous point, we simply tested the E6700 and QX6700 with 8x333 + DDR2-833 instead of 10x266 + DDR2-800 with 3ds Max and TMPGEnc. These applications really take advantage of the multithread, but do not require the highest bandwidth.
By increasing to FSB1333, we didn’t measure any performance improvements with the E6700 and we measured small ones with the QX6700 in this test. So, if there are some restrictions due to this FSB, this isn´t where the problem is. There were two possibilities. It could be a memory bandwidth problem and in this case DDR3 will be the solution. However, more likely software isn´t yet capable of fully using 4 cores, because multithreading is still limited.
