IBM POWER8 CDIMM Memory Voltage Regulator Card (FRU: 01AF090)

1. Product Overview & Description

The 01AF090 is a specialized power distribution and voltage regulation module designed for IBM’s enterprise “Big Iron” scale-out infrastructure. It sits directly on the system node processor/memory planar to step down and tightly regulate the DC voltage supplied to the high-bandwidth DDR3/DDR4 CDIMMs (Custom Dual Inline Memory Modules) and their corresponding Centaur memory buffer chips.

Attribute	Specification
IBM FRU Part Number	01AF090
Product Description	Memory Voltage Regulator Module (VRM) / Memory Power Card
Component Architecture	IBM POWER8 High-End Enterprise Subsystem
Form Factor	Proprietary Vertical Plugin Module (Riser Card)
Hot-Swappable / Redundant	Dependent on node configuration guidelines

2. Server Compatibility Profile

This specific module is strictly engineered for the multi-node enterprise POWER8 framework. It is not compatible with standard scale-out servers (e.g., S814, S822, S824).

IBM Power System E880 (9119-MHE)
IBM Power System E880C (9119-MHE)
IBM Power System E870 (9119-MME)
IBM Power System E870C (9119-MME)

3. Technical Role in the E880 / E870 Memory Subsystem

The IBM Power E880 memory architecture relies on a unique topology where memory controllers on the POWER8 chip communicate via high-speed channels to Centaur buffer chips embedded right on the memory cards.

Voltage Stabilization: Steps down bulk power input from the system’s power supplies to the specific ultra-low voltages ( $1.35\text{V}$ – $1.5\text{V}$ for DDR3 CDIMMs or $1.2\text{V}$ for DDR4 CDIMMs) needed by memory arrays and buffer modules.
High-Bandwidth Support: Supplies stable power necessary to sustain up to 230 GB/s of sustained memory bandwidth per socket.
Thermal & Power Monitoring: Communicates telemetry data back to the Flexible Service Processor (FSP) via the $I^2C$ /SMBus interface for real-time monitoring of power efficiency and thermal thresholds.

4. Associated System Features (Memory Context)

When managing or configuring memory components on the E880 system nodes where this VRM resides, the module powers memory configurations following these capacities:

Memory Slots Covered: Up to 32 CDIMM slots per 5U System Node.
Supported Memory Sizes (DDR3/DDR4 CDIMMs):
- 64 GB (4x16GB) — Feature Code: EM8J
- 128 GB (4x32GB) — Feature Code: EM8K
- 256 GB (4x64GB) — Feature Code: EM8L
- 512 GB (4x128GB) — Feature Code: EM8M
- 1024 GB (4x256GB DDR4) — Feature Code: EM8Y
Maximum Memory Supported: Up to 8 TB per system node (or up to 32 TB across a fully scaled 4-node E880 system).