Dell PowerEdge 6650

Memory Technology

The PowerEdge 6650 system utilizes PC1600 (1.6GB/s PEAK transfer rate) or DDR200 (Double Data Rate at 200MHz) memory technology.

The PowerEdge 6650 memory system resides on two separate memory riser cards, which are attached to the processor system board via a single 216-pin HDM+ connector. Part of the GC chipset (two REMC chips) resides on each Memory Card to drive the data to the DDR SDRAM DIMMs. The REMC address control chip is on the processor tray. The two memory cards together provide a 4 DIMM (288-bit) wide memory port.

Both memory cards must be populated in all configurations.

DDR Memory

DDR (Double Data Rate) is the next generation SDRAM standard using a double data rate clocking technique to push its peak burst bandwidth to 1.6 GB/s as compared to 1 GB/s for PC133 SDRAM. This performance advantage will immediately be appreciated in high-end graphics applications and in other high performance and memory intensive deployments.

The manufacturing process for DDR-SDRAM is very similar to that of SDRAM, except for higher speed testers, and therefore does not require new equipment, training, or validation. This allows higher bandwidth DDR-SDRAM to be produced at a reasonable cost.

The PowerEdge 6650 provides PC1600 (or DDR200) memory DIMMs with 128MB, 256, 512 and 1GB capacities. In all the system configurations DIMMs must be installed in sets of four.

DIMM memory support

The PowerEdge 6650 contains two memory riser cards, each with up to eight memory modules. The memory riser card provides 8 72-bit (168-pin) sockets for DIMM memory modules. These modules are PC200 DDR SDRAM DIMMs. ECC is checked and generated within the chipset and the memory system is designed for DRAM 'ChipKill' support.

The DRAM interface provides support for 64, 128, 256, and 512-Mbit (when available) technologies, which will allow up to 128/256/512/1GB/2GB per DIMM socket (double-sided DIMM) and a maximum memory size of 32GB.

NOTE: At first shipment of the PowerEdge 6650, 512-Mbit DRAM technology is not yet available, so the maximum supported memory of the PowerEdge 6600 and PowerEdge 6650 until then will be 16GB using stacked 1GB DIMMs.

Memory Configuration

• The DIMMs need to be inserted in sets of four (there are four banks, each consisting of four interleaved DIMMs).
• One bank consists of two DIMMs on each memory card.
• The PowerEdge 6600 and PowerEdge 6650 will support any combination of memory sizes as long as each bank has the same memory size.
• As an example you could have 1 bank of 512MB DIMMs(4), and another bank with 1GB DIMMs (4).
• The banks must be populated in order so that if only one bank is present it is bank 1.

Memory Module Installation Guidelines

The memory modules are contained on two memory riser cards. Each riser card has eight memory module sockets. Between the two memory riser cards, the system can accommodate from 512 MB to 16 GB of registered memory. The memory module sockets on each riser card are arranged in pairs (A and B) on four banks (1-4). Memory modules must be installed in at least one bank on each memory riser card for the system to operate. The memory modules should be installed starting with bank 1 and ending with bank 4. Each bank on each memory riser card must contain the same memory module size. For example, if bank 1 on one riser card contains 128-MB memory modules, bank 1 on the other riser card must also contain 128-MB memory modules.

To obtain the desired total memory for the system, it may be necessary to install memory modules of different sizes. This is supported as long as the memory modules installed in each bank are the same size. For example, with 6 GB of total memory in the system, each memory riser card configuration could be as follows:

Memory Riser Card A

Memory Riser Card B

	Bank 1 = 2 GB		Bank 2 = 1 GB
	Bank 1 = 2 GB		Bank 2 = 1 GB

Memory module sockets are arranged in pairs, labeled A and B, on each memory riser card. A pair of sockets on each memory riser card forms a single memory bank. When installing memory modules, you should adhere to the following guidelines:

• Each bank must contain identical modules. You must install memory modules in matched sets of four, two in each memory riser card
• Install identical memory modules in sockets A and B for bank 1 before installing modules in sockets for bank 2, and so on.
• Memory banks must be populated sequentially, which means that there can be no empty banks between the first and last populated banks.

NOTE: The DIMMs need to be inserted in sets of four (there are four banks, each consisting of four interleaved DIMMs). One bank consists of two DIMMs on each memory card. The banks must be populated in order so that if only one bank is present it is bank 1.

Sample Memory Module Configurations

Total Desired Memory	BANK1		BANK2		BANK3		BANK4
	A	B	A	B	A	B	A	B

512 MB	128 MB	128 MB	None	None	None	None	None	None
1 GB	128 MB	128 MB	128 MB	128 MB	None	None	None	None
1 GB	256 MB	256 MB	None	None	None	None	None	None
2 GB	512 MB	512 MB	None	None	None	None	None	None
4 GB	512 MB	512 MB	512 MB	512 MB	None	None	None	None
4 GB	1 GB	1 GB	None	None	None	None	None	None
6 GB	1 GB	1 GB	512 MB	512 MB	None	None	None	None
12 GB	1 GB	1 GB	1 GB	1 GB	1 GB	1 GB	None	None
14 GB	1 GB	1 GB	1 GB	1 GB	1 GB	1 GB	512 MB	512 MB
16 GB	1 GB	1 GB	1 GB	1 GB	1 GB	1 GB	1 GB	1 GB

NOTE: This table is a sample configuration of just one memory riser card. For the total desired memory, both riser cards must be configured identically with the same memory module sizes.

Redundant Memory Features

ChipKill - ECC is checked and generated within the chipset, and the memory system is designed for DRAM 'ChipKill' support. This means that if the memory system is populated with either x4 or x8 DRAMs (4 bit or 8 bit DRAM devices), then the failure of any DRAM device will not cause uncorrectable data errors. This is accomplished by spreading 2 144-bit ECC words across 4 DIMMs (32 bytes). Each ECC word has the capability of correcting any single bit error or any 4 adjacent bits (nibble). For a system using x8 DRAM devices, the two nibbles for each DRAM are from separate ECC words. If x16 DRAM devices are used then the ChipKill feature is not present although the system operation is unaffected. The PowerEdge 6650 system will only ship with DIMMs that have chip kill support.

Spare Bank Memory - This feature is supported if the memory cards are populated with either 3 or 4 banks (12 or 16 DIMMs) of identical DIMMs and is enabled/disabled through BIOS Setup. When enabled, one of the banks of memory is designated as a 'Spare Bank' and is not actively used by the system. The BIOS reports the total memory size to the OS as not including this spare bank. If several single-bit errors (correctable) are generated from a memory bank in a short amount of time, the BIOS will initiate (through the chipset) a copy of all data from this faulty DIMM bank to the spare bank. This action will be transparent to the OS and any software applications running. The benefit of Spare Bank Memory is to prevent a faulty memory DIMM that is creating single-bit errors from degrading into a fatal multi-bit error that would crash the system.

Memory Mirror - This feature is supported if the memory cards are populated with 4 banks (16 DIMMs) of identical DIMMs and is enabled/disabled through BIOS Setup. When enabled, two of the banks of memory are designated as a 'Memory Mirror' and are not actively used by the system. The BIOS reports the total memory size to the OS as not including this 'Secondary Mirror'. When enabled, all writes to memory are sent to both mirrors by the chipset. All reads are from the primary mirror. If a multi-bit error (normally uncorrectable) is discovered on a read from the primary mirror the chipset will automatically replace this faulty data with data from the secondary mirror. The chipset will switch to the secondary mirror for further reads leaving the faulty primary mirror unused. The feature allows the system to survive a multi-bit error that is normally fatal to servers even with ECC protection.