HP ProLiant AMD-based 300-series G7 servers

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speed and transfer rate increased from 800 MHz (1.6 MT/s
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) to a maximum of 3.2 GHz (6.4 GT/s)
in each direction.
The G34 socket infrastructure features four, 16-bit HT3 links operating at up to 6.4 GT/s per link. Of
the four HT3 links, three are shared processor to processor links and one link on processor one is
used for I/O communication.
HT Assist
HT Assist reduces cache coherence traffic on the HT links. By tracking where data is stored in cache
and guiding the processor directly to the cache of other processors, HT Assist reduces cache probe
traffic between processors, especially in 4- socket servers. Therefore, HT Assist results in faster queries
that can increase performance for cache-sensitive applications such as database, virtualization, and
compute-intensive applications.
Memory technologies
In the AMD Opteron 6100-series architecture, the memory controller is integrated into the processor
chip to optimize memory performance and bandwidth per CPU. The memory controller reduces
latency inherent in front side bus architectures by eliminating the bus contention between memory and
I/O cycles. A server’s overall memory bandwidth increases as processors are added to a
configuration, unlike legacy designs that scale poorly because access to main memory is limited by
external Northbridge chips. HP designed specific BIOS and RBSU functions to manage memory
configurations, letting the customer optimize configurations for maximum performance while reducing
power consumption and cooling requirements. These management options also include memory
protection and latency reduction. Because of the increased reliability of DDR3 on-DIMM thermal
sensors, HP incorporates DIMM thermal data into the algorithms controlling thermal and power states
within the server.
DDR3 DIMM choices
HP ProLiant 300-series G7 servers with Opteron 6100 series processors support double data rate
(DDR3) DIMMs. DDR3 has several key enhancements including an 8-bit prefetch buffer for storing
data before it is requested. By comparison, DDR-2 has a 4-bit buffer. For DDR3, the data signal rate
can increase to 1333 Megatransfers per second (MT/s). While this is commonly referred to as having
a speed of 1333 MHz, the maximum clock speed for the DIMMs is actually 667 MHz and the signal
is double-pumped to achieve the 1333 MT/s data rate. DDR3-1333 DIMMs can operate at clock
speeds of 667 MHz, 533 MHz, and 400 MHz with corresponding data rates of 1333, 1066, and
800 MT/s.
HP DDR3 DIMM modules incorporate an integrated thermal sensor that signals the processor to
throttle memory traffic to the DIMM if its temperature exceeds a programmable critical trip point.
Using the data from these thermal sensors, ProLiant AMD-based 300-series G7 servers can reduce fan
speed when memory is idle, which reduces power consumption. The BIOS in ProLiant G7 servers
verifies the presence of the thermal DIMM sensor during POST. Some third-party DIMMs may not
include this thermal sensor. If it is absent, a POST message will warn that the DIMM does not have a
thermal sensor, and the fans will be forced to run at higher speeds (requiring more power).
DDR3 is available as both Unbuffered Dual In-line Memory Modules (UDIMMs) and Registered
(buffered) Dual In-line Memory Modules (RDIMMs). Both RDIMMs and UDIMMs support error
correcting code (ECC).
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MT/s, or megatransfers per second, equals the speed of the link in millions of cycles per second times the number of transfers
per cycle.