post #1 of 1
Thread Starter 
So last November around the time of the Sandy Bridge-E launch, there were reports of a "D? Stepping" for Sandy Bridge-E, to succeed the C1 and C2 steppings that were known at the time. I believe that since then, we have heard nothing regarding this potential new stepping, and the idea has faded into obscurity.

I'm tossing out a theory of mine, since tomorrow is supposed to be the launch day for the E5-4600, E5-2400, and E3-1200 V2 series Xeon processors. I'm betting that the E5-4600 series will launch with a new stepping. Presumably it will be Stepping 8, or D0. The timing fits nicely with the full base layer respin for Nehalem. About four months passed between the launch of the consumer grade C0 stepping, and the server grade D0 stepping. Now three and a half months have also passed since the January 30th announced availability of the Sandy Bridge-E C2 stepping.

The strongest evidence for a new stepping after C2 is in Intel's MDDS database. That database indicates that there was a production run of E5-2600 series Xeons at the C1 stepping, presumably for NDA customers. The launch stepping for those Xeons was C2.

Now, for the E5-4600 series Xeons, I suggest that the same thing as happened. If you search in that database for CM8062107184516, the Product Code for the E5-4650, three listings are present with separate S-Specs (SR0JH, SR0KJ, and SR0TS). Though not always, different S-Spec codes generally indicate different steppings of a processor

SR0JH was listed on 9/15/2011, around the same time as other C1 stepping S-Specs. Presumably it is part of a C1 production run of E5-4600 series processors. SR0KJ was listed on 10/08/2011, around the same time as other C2 stepping S-Specs. It also aligns closely with S-Specs for launched C2 stepping processors. For example, the E5-2670 is SR0KX. On 3/10/2012, Intel listed a third S-Spec for the E5-4650: SR0TS. I propose that this is the S-Spec for a new stepping, perhaps D0, for Sandy Bridge-EP. A full base layer respin like that would explain the delay of the four-way processing E5-4600 series to now. Perhaps Intel didn't feel comfortable using the C2 stepping for such mission critical applications, where it would compete with Itanium and IBM's Power architecture.

If there is indeed a new stepping, it will be interesting to see if if brings any benefits and if it will be brought to the desktop market. Presumably if new masks have been made for the stepping, it would make sense to use them across all markets for Sandy Bridge-EP die.