When selecting ECC RDIMMs for the ASRock X99 OC Formula motherboard, particularly in a setup using a Haswell-E CPU, it's important to understand the requirement for 8-bit organization in the memory modules.
8-bit Organization: Memory modules are organized based on how data is structured and accessed. ECC RDIMMs with 8-bit organization refer to the width of the data bus for each memory chip on the module. In simpler terms, each memory chip on the RDIMM is structured to handle 8 bits of data at a time. This organization is crucial because the memory controller in the Haswell-generation CPU is designed to work with modules that follow this structure. The CPU's memory controller handles the data exchange between the memory and the system, and it requires 8-bit organization for proper communication and stability.
Why It Matters: Some RDIMMs use 4-bit or 16-bit organization, which is more common in server-grade memory for large-scale systems. However, motherboards like the X99 OC Formula typically require 8-bit organization to ensure proper communication between the memory and the CPU. Using RDIMMs with a different organization (e.g., 4-bit or 16-bit) results in compatibility issues, and the system not recognizing the memory.
Compatibility with X99: Since the X99 OC Formula is not primarily designed for server environments but rather for high-performance consumer or workstation use, it adheres to more typical memory standards found in desktop systems. This makes 8-bit ECC RDIMMs more suitable for this board. Using RDIMMs with a different organization (e.g., 4-bit or 16-bit) would cause incompatibility, as the manual specifically states that 8-bit memory is required for proper operation.
ECC RDIMM Selection: When selecting 32GB ECC RDIMMs for this board, it’s important to check not only for ECC support but also for the memory’s internal organization. 8-bit ECC RDIMMs ensure the memory can be utilized properly by the X99 OC Formula’s memory controller without causing errors or performance degradation. The terms 1Rx8 and 2Rx8 refer to the memory’s rank and chip organization. 1Rx8 means the memory module is single-ranked, with each rank consisting of chips that are organized in an 8-bit wide configuration. 2Rx8 means the module is dual-ranked, with two sets of memory chips organized in an 8-bit wide configuration. Both 1Rx8 and 2Rx8 modules are compatible with the X99 OC Formula motherboard, as they meet the required 8-bit organization standard.
256 GB Maximum Capacity: The X99 OC Formula motherboard features 8 DIMM slots, and with each slot supporting a maximum of 32GB DDR4 modules, this results in a total possible capacity of 256 GB (8 slots x 32 GB per module). This is a common capacity limit for high-end X99 boards when utilizing large-capacity memory modules.
Selecting 8-bit ECC RDIMMs is a crucial requirement for compatibility with the ASRock X99 OC Formula motherboard. Memory with other organizations, such as 4-bit or 16-bit, will not work correctly due to differences in how data is handled between the memory and the system's memory controller. Therefore, checking the data organization of the RDIMMs is essential to ensure stable and functional memory performance.
Samsung 32GB ECC RDIMM 2Rx8 Memory
Part Number: M393A4G43AB3-CWE
BIOS Verions tested P1.10 and P2.00
Board would not POST with BIOS P3.40
dmidecode 3.4 Getting SMBIOS data from sysfs. SMBIOS 2.8 present.
Handle 0x0011, DMI type 16, 23 bytes Physical Memory Array Location: System Board Or Motherboard Use: System Memory Error Correction Type: Multi-bit ECC Maximum Capacity: 256 GB Error Information Handle: Not Provided Number Of Devices: 4
Handle 0x0013, DMI type 17, 34 bytes Memory Device Array Handle: 0x0011 Error Information Handle: Not Provided Total Width: 72 bits Data Width: 64 bits Size: 32 GB Form Factor: DIMM Set: None Locator: DIMM_A1 Bank Locator: NODE 1 Type: Other Type Detail: Synchronous Speed: 2133 MT/s Manufacturer: Samsung Serial Number: 46335501 Asset Tag: DIMM_A1_AssetTag Part Number: M393A4G43AB3-CWE Rank: 2 Configured Memory Speed: 2133 MT/s