All the leading itanuim vendors are moving to the new processor that has been launched by Intel called Nehalem Ex Xeon 7500 processors for its big iron beasts. Although HP has not done so at this point in time!
At one point of time, NEC made a great deal about the high end itanium based systems in the last decade. It was able to gain a large amount of gains because of its 16-socket Azuza and the 32-socket Azama machines in the Express 5800 family and all of them had a family of chipsets.

But to the modern time, NEC is trying really hard to get to its niche audience quickly and to give them differentiation when compared to the others who are getting Nehalem-EX boxes. Mike Mitsch, the General Manager for the IT Platform Group at NEC America had this to say that the engineers did take some of the RAS good things from the Itanuim version and its A3 chipset and put them into the new Express5800 GX series. This uses the Xeon 7500 processors.

This is the same idea as at the time when the Xeon 7500s were introduced into the market. They are the same as itanium and the only difference being that this time you might be able to actually use them.
The Express 5800 Glueless Xeon GX servers have been designed from scratch by NEC. They have not been developed in collaboration with Unisys. Unlike the Monster Xeon MX machines which use four core and six core Xeon 7400 processors, this was introduced in September 2008.

The Express5800 MX machines are cell-based and symmetric multi-processing systems. These are based on the working of four-socket mobos. The entire monster Xeon server chassis has a four socket-cell and the other four chassis are put together using the external SMP links. This makes up the 96 core box which is called the Express5800/A1160 MX server in its easy to remember name.

The MX chipset that is in use in the server sports 80GB/sec of bandwidth to connect the main and cache memories on the four server nodes and to the SMP configuration. The box can hold 1 TB of main memory and uses 8 GB fully buffered DDR2 memory sticks.

The monster Xeon server that has been made by NEC and Unisys but manufactured only by NEC, works on four core and six core Dunnington Xeon 7400 processors. The architecture in use is the same as used in the front side of buses of new QucikPath interconnect that the Nehalem and now even the Westmere Xeon chips use.

Rather than just pick the MX chipset and refit it, NEC instead went ahead and designed them right from scratch and build the gluelessly scales from two to four sockets and that to in a single system.
With all the other IT companies catching up, NEC wanted to be in the forerun and hence went about with this glueless GX design instead.