IBM 86884RX Installation Guide - Page 58

PCI slot configuration, Bus C slot 5: One 64-bit 133 MHz slot

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If there is a mismatch between the total memory in port 1 and the total memory in port 2, then there will be a delay when accessing the upper memory. For example if you have two 512 MB DIMMs and two 1 GB DIMMs, memory accesses to the first 2 GB of memory (1 GB from each port) will be at maximum rate of 6.4 GBps. However, the remaining 1 GB (the upper half of the 1 GB DIMMs) will only be at 3.2 GBps maximum. 3.1.3 PCI slot configuration As shown in Figure 1-1 on page 4, there are six PCI-X slots internal to the x450. These six slots are implemented using four PCI buses: Bus A (slot 1 and slot 2): Two 64-bit 66 MHz slots Bus B (slot 3 and slot 4): Two 64-bit 100 MHz slots (133 MHz if only one slot is occupied) Bus C (slot 5): One 64-bit 133 MHz slot Bus D (slot 6): One 64-bit 133 MHz slot These slots can accept adapters rated at speeds ranging from 33 MHz to 133 MHz. You should also consider the following: Each adapter has a maximum rated speed. Each bus also has a maximum rated speed. Installed adapters in a single bus will operate at the slowest of three speeds: - The rated speed of adapter 1 - The rated speed of adapter 2 (if the bus the adapter is installed in has two slots) - The rated speed of the bus Bus B supports one adapter at up to 133 MHz or two adapters at up to 100 MHz. 32-bit adapters can be installed in any of the slots and will run in 32-bit mode. 32-bit and 64-bit adapters can coexist in 64-bit slots in the same bus. The 32-bit adapters will run in 32-bit mode, and the 64-bit adapters will run in 64-bit mode. Tip: Take the time to understand these rules and to select the best slots for your adapters. Incorrect choices can result in a loss of PCI adapter performance. 44 IBM ^ xSeries 450 Planning and Installation Guide

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44
IBM
^
xSeries 450 Planning and Installation Guide
If there is a mismatch between the total memory in port 1 and the total memory in
port 2, then there will be a delay when accessing the upper memory. For example
if you have two 512 MB DIMMs and two 1 GB DIMMs, memory accesses to the
first 2 GB of memory (1 GB from each port) will be at maximum rate of 6.4 GBps.
However, the remaining 1 GB (the upper half of the 1 GB DIMMs) will only be at
3.2 GBps maximum.
3.1.3
PCI slot configuration
As shown in Figure 1-1 on page 4, there are six PCI-X slots internal to the x450.
These six slots are implemented using four PCI buses:
±
Bus A (slot 1 and slot 2): Two 64-bit 66 MHz slots
±
Bus B (slot 3 and slot 4): Two 64-bit 100 MHz slots (133 MHz if only one slot is
occupied)
±
Bus C (slot 5): One 64-bit 133 MHz slot
±
Bus D (slot 6): One 64-bit 133 MHz slot
These slots can accept adapters rated at speeds ranging from 33 MHz to 133
MHz.
You should also consider the following:
±
Each adapter has a maximum rated speed. Each bus also has a maximum
rated speed.
±
Installed adapters in a single bus will operate at the slowest of three speeds:
–
The rated speed of adapter 1
–
The rated speed of adapter 2 (if the bus the adapter is installed in has two
slots)
–
The rated speed of the bus
±
Bus B supports one adapter at up to 133 MHz or two adapters at up to 100
MHz.
±
32-bit adapters can be installed in any of the slots and will run in 32-bit mode.
32-bit and 64-bit adapters can coexist in 64-bit slots in the same bus. The
32-bit adapters will run in 32-bit mode, and the 64-bit adapters will run in
64-bit mode.
Tip:
Take the time to understand these rules and to select the best slots for
your adapters. Incorrect choices can result in a loss of PCI adapter
performance.