1. Competitive Advantage of Registered Memory
Capacity at competitive price
Registered DIMMs allow stacking of RAM parts. Thus higher DIMM capacities are possible with Registered DIMMs, allowing higher total system memory capacity.
Stacked DIMMs are constructed with lower density RAM chips for a given DIMM size, meaning stacked DIMMs cost significantly less than Unbuffered DIMMs at higher capacities.
DIMM Capacities on High End
128 MB
256 MB
512 MB
1 GB
2 GB
Unbuffered
~$45
~$125
~$250
~$1,350
(Dell doesn’t offer)
Not
Available!
Registered (HP)
$40
$125
$250
$970 (stacked)
$2,800 (stacked)
1/2/2019
HP Confidential

2. Memory – Registered vs. Unbuffered
1/2/2019
Memory – Registered vs. Unbuffered
What:
Registered DIMMS have a register to store control signals (Chip Select, RAS, CAS, etc.) to the RAMs. This is required for some ram chips and DIMM configurations for Electrical Timing reasons.
Unbuffered DIMMs have no register or buffer – the RAM chip control signals are connected directly to the data bus
Chips
RAM
Chips
RAM
Control Signal Register
Control
Control
Data
Data
Registered DIMMs
Unbuffered DIMMs
1/2/2019
HP Confidential
HP template

3. Memory – Pictures of DIMMs
1/2/2019
Memory – Pictures of DIMMs
512MB Unbuffered DIMM Non-ECC
512MB Registered DIMM ECC
Control Signal Register & PLL
1/2/2019
HP Confidential
HP template

4. Memory – Registered vs. Unbuffered
1/2/2019
Memory – Registered vs. Unbuffered
Cost
Registered DIMMs are typically constructed with lower density RAM chips for a given DIMM size. Because of RAM cost drops over time, this means Registered DIMMs cost significantly less than Unbuffered DIMMs for the same capacity.
Capacity
Registered DIMMs allow stacking of RAM parts. Thus higher DIMM capacities are possible at any given time with Registered DIMMs. This allows higher total system memory capacity.
Performance
This is a mixed bag. Unbuffered DIMMs have lower latency as there is no delay through the Register. However, Registered DIMMs typically allow more “open pages” due to the larger number of RAM chips, and that can result in higher performance.
Summary – Regstered DIMMs are typically the right answer for the customer
Registered Unbuffered
Price per 1GB DIMM $970 $1350
Performance ~1x ~1x
1/2/2019
HP Confidential
HP template