1u's with the Xeon 7500's when?

The successor to the 2950 is actually the R710. You can buy these with 2 6-core processors (Xeon X5600-series) and these support 18 dimms (up to 192GB).

Dell has the M910, which is a double wide blade server, and therefor would allow up to 8 of these in an M1000e blade chassis.

Because Xeon 7500 processors are made for building 4-processor systems, servers that use that many processors tend to also use (be capable of using) quite a bit of memory. Trying to fit 4 processor sockets, 32+ dimm slots and powersupplies to feed all this into 1U is kind of tough. If you don't want a blade chassis, but do want specifically the Xeon 7500 series processors, your choice is limited to the R910 (4U though, partially due to the 64 dimm slots (on risers)).

There is also the 2U R810 that can be configured with the 7500 series - are you dead-set on 1U units?

http://www.dell.com/us/en/business/servers/poweredge-r810/pd.aspx?refid=poweredge-r810&s=bsd&cs=04

Thanks guys. I am aware of the r710's. We have a ton of them, literally.

I was only interested in the 1u for rack consolidation over the 2u's. I did not realize the 7500 series were not or would not be made available in the 1u chassis.

Actually the R710 will not accept the 7500 series - just the R810 and R910.  I suspect that there will soon be a 1U server with them, as they are obviously not restricted to 4-socket configurations.