D0 Processor Stepping and Performance
Intel sent out the note on the new D0 processor stepping to all partners back in January. However that official document offered no juicy details.
The only things they revealed included the changed S-Spec part number, CPUID identifier and slight modifications of the CPU exterior looks. As for everything else, Intel responded archly: the specs wouldn’t change. But specs are specs, and what do we have in reality? For example, some think that the new processor stepping comes with a modified memory controller.
It is actually very easy to check out: we just have to see how fast two Core i7-920 processors (with the old and new processor stepping) work with the memory. To ensure that the differences would be more obvious, we ran the tests with both processors overclocked to 4.0GHz (20 x 200MHz) and memory configured as DDR3-1600 with 8-8-8-24 timings. The North Bridge integrated into the processor worked at 3.2GHz in both cases.
The results of our memory subsystem test show clearly that we shouldn’t expect CPUs with new processor stepping to perform any different. The differences we see in obtained results are all within the measuring error.
Well, it means that we should actually look for changes in power consumption and overclocking first. We have already confirmed in our First Look at Core i7-975 XE article that new processor stepping will bring some changes in these aspects. Let’s try and double-check our findings once again, especially since we now have preproduction processors available to us, and not engineering samples.