Dimm Types; Dual Channel Ddr Overview; Dimm Connector Styles Supported - Intel Xeon Design Manual

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Intel Xeon™ Processor and Intel
3.1

DIMM Types

To allow flexibility in platform design this design guide supports three different DIMM connector
types: 0-degree, 25-degree and 90-degree (see
DIMM connector type in the following sections.
Figure 8. DIMM Connector Styles Supported
3.2

Dual Channel DDR Overview

In a dual channel DDR configuration, channel A and B are active and operate in lock-step which
logically appears to be one 144-bit wide memory bus; however, each channel is separate
electrically.
The letters 'A' and 'B' in the DIMM figure refer to the DIMM channel. The number following 'A'
or 'B' refers to the DIMM logical group. The DIMMs are physically interleaved. Intel recommends
using this ordering, starting with Channel B closest to the MCH, for optimal routing.
The platform requires DDR DIMMs to be populated in-order, starting with the two DIMMs
furthest from the MCH in a 'fill-farthest' approach (see
on the signal integrity requirements of the DDR interface. Intel's recommendation is to check for
correct DIMM placement during BIOS initialization. Additionally, it is strongly recommended that
all designs follow the DIMM ordering, SMBus Addressing, Command Clock routing and Chip
Select routing documented in
compliant with the reference BIOS code supplied by Intel.
22
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E7500/E7501 Chipset Compatible Platform
Figure 9 and Figure 10 show both channels being routed to a single bank of DIMMs.
Figure 9
Figure 8). Routing guidelines are provided for each
Motherboard
DIMM
Motherboard
DIMM
Motherboard
Figure 10). This recommendation is based
and Figure 10. This addressing must be maintained to be
Platform Design Guide Addendum
DIMM
90° DIMM Connector
25° DIMM Connector
0° DIMM Connector