With our recent discussion regarding Intel’s launch of the 15-core Xeon E7 v2 ‘IvyTown’ processors, thoughts for a lot of high end consumers focused on the underlying hardware for these 4P and 8P systems that would be entering the market. Previously with high end systems there has been a disjunct between the sockets used for the mainstream 1P and 2P processors (-E and -EP) compared to the higher end 4P/8P models (-EX). For example:

With Nehalem/Westmere, the single socket Bloomfield Xeons were LGA 1366.

With Nehalem-EP/Westmere-EP, the dual socket Gainstown Xeons were also LGA 1366.

With Nehalem-EX/Westmere-EX, the quad/octo socket Beckton Xeons were LGA 1567.

With Sandy Bridge-E/Ivy Bridge-E, the single socket Xeons are LGA 2011.

With Sandy Bridge-EN/Ivy Bridge-EN, the single/dual socket Xeons are LGA1356

With Sandy Bridge-EP/Ivy Bridge-EP, the dual socket Xeons are LGA 2011.

With Ivy Bridge-EX, the quad/octo socket Xeons are also LGA 2011, but different.

Reported images of Haswell-EP Xeons also point to LGA 2011, but different again.

Back at ISSCC, when we reported about the talk around the new IvyTown based processors, we lifted the following line from the official documentation:

“The processor supports two 2011-land, 40-mil pitch organic flip-chip LGA package options”

This produced speculation to whether the processor package for EX would be the same as EP, despite a reconfigured memory controller, additional QPI links and a different pin layout. Given at the time we were under NDA we could not mention they were different, but some investigative work from Patrick at ServeTheHome answers a lot of questions.

Simply put, Ivy Bridge-EP, Ivy Bridge-EX and Haswell-EP all have LGA2011 designations (officially FCLGA2011, for flip-chips), but have different physical mountings in the socket:

Despite the contact patches/‘wings’ on Ivy Bridge-EP, it will fit in the Sandy Bridge-EP socket – the issue is more the pins on Ivy Bridge-EX and Haswell-EP, where on the left and right it is more ‘filled in’, as well as at the corners. The notches for the processors (the indents on the top and bottom) are also different, moving to Ivy Bridge-EX.

The Ivy Bridge-EX and Haswell-EP processors look very similar from these images, despite the extra wings on the Haswell-EP. The key here is the bottom right of the two processors, and count the number of pins between the notch and the edge – Ivy Bridge-EX has four, Haswell-EP has six.

All in all, this may not much of anything – users spending thousands on processors should be making sure that the motherboards they buy have the processor they want listed in the QVL (Qualified Vendor’s List). My concern might be users thinking they can drop a Haswell-EP Xeon into an Ivy Bridge-E, and then trying to force it when it might not fit. Back in previous eras (socket 775 comes to mind) this was an even bigger issue – the processors might fit, but the processors that a motherboard could take was determined by the chipset used by the motherboard manufacturer and the QVL. At least this way the CPUs will not physically fit, but it is something that confuses the situation – it might be worth doing some clever renaming (LGA2011-EX, LGA2011-H), at least from an editorial point of view for the future.

Source: ServeTheHome