IBM 250000 - Manual (Page 5)

Leadership enterprise server with significantly lower cost of ownership in a highly available and
expandable, rack-dense, 1U dual-socket server
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5
a 2.26GHz processor can run the cores at 2.4GHz. With only one or two cores active, the same
processor can run those cores at 2.53GHz. Similarly, a 2.93GHz processor can run at 3.06GHz
or even 3.33GHz. When the cores are needed again, they are dynamically turned back on and
the processor frequency is adjusted accordingly.
Intel Extended Memory 64 Technology (EM64T) 64-bit extensions allow the Xeon processor to
use large memory addressing when running with a 64-bit operating system. This in turn lets
individual software processes directly access more than 4GB of RAM, which was the limit of 32-
bit addressing. This can result in much higher performance for certain kinds of programs, such as
database management and CAD. Additional registers and instructions (SSE3) can further boost
performance for applications written to use them. Contact your software provider to determine
their software support for EM64T.
Intelligent Power Capability powers individual processor elements on and off as needed, to
reduce power draw.
Execute Disable Bit functionality can help prevent certain classes of malicious buffer overflow
attacks when combined with a supporting operating system.
DDR-3 Registered Memory with Chipkill ECC Protection
The x3550 M2 ships with registered double data rate III (DDR-3) memory and provides Active
Memory features, including advanced Chipkill memory protection (optionally), for up to 16X
better error correction than standard ECC memory. In addition to offering better performance than
DDR-2 or fully-buffered memory, DDR-3 memory also uses less energy. DDR-2 memory already
offered up to 37% lower energy use than fully buffered memory. Now, a generation later, DDR-3
memory is even more efficient, using 22% less energy than DDR-2 memory.
The x3550 M2 supports up to 128GB of memory in sixteen DIMM slots. Redesign in the
architecture of the Xeon 5500 series processors bring radical changes in the way memory works
in these servers. For example, the Xeon 5500 series processor integrates the memory
controller inside the processor, resulting in two memory controllers in a 2-socket system. Each
memory controller has three memory channels. Depending on the type of memory, population of
memory, and processor model, the memory may be clocked at 1333MHz, 1066MHz or 800MHz.
Note: If only one processor is installed, only the first eight DIMM slots can be used. Adding a
second processor not only doubles the amount of memory available for use, but also doubles the
number of memory controllers, thus doubling the system memory bandwidth. If you add a second
processor, but no additional memory for the second processor, the second processor has to
access the memory from the first processor “remotely,” resulting in longer latencies and lower
performance. The latency to access remote memory is almost 75% higher than local memory
access. So, the goal should be to always populate both processors with memory.
The X55xx models support up to 1333MHz memory clock speed, while the E55xx-and-up and
L55xx-and-up models support up to 1066MHz clock speed, and the E550x models support
800MHz clock speed. Using 1333MHz memory (where supported) versus 1066MHz offers up to
9% better performance, while 1066MHz memory produces up to 28% better performance than
800MHz memory.
Xeon 5550 series processors access memory with almost 50% lower latency than the previous
generation 5400 series processors. That can result in faster processing of latency-sensitive
workloads.
Ch1 Ch0 Ch2 Ch1 Ch0 Ch2
Xeon 5500
Processor 0
Memory Controller
7
4
6
3
8
5
Xeon 5500
Processor 1
14
11
QPI
Memory Controller
1 2
15
12
16
13
9 10
D1
D2
D3
D4
D5
D6
D7
D8
D9
D10
D11
D12
D13
D14
D15
D16
1-16: DIMM population sequence , D1-D16: DIMM slot assignments