MemTest86 Technical Information

DIMM / Chip error decoding (Pro & Site Edition only)

• Chip numbering convention
• Supported module types
• Supported platforms

MemTest86 V10 (Pro Edition) supports decoding and identification of the DDR5/DIMM module on which a particular error occurred. This can be used to more efficiently narrow down potentially bad RAM modules. This is done by decoding the memory address with an error and locating the physical hardware that corresponds to that address. The possibiliity of multiple channels, multiple ranks, interleaving & hashing of addresses makes this a complex process.

If supported, MemTest86 reports the decoded DIMM and DRAM chip when memory errors are detected during testing. In additional, a graphical summary report of memory errors for each module is displayed on test completion (shown below), as well as in the HTML report.

Note that due to the nature of the tests, accurate slot and chip decoding is not possible for test 6 or test 14. Due to this, no errors found during either test are decoded.

Chip numbering convention

MemTest86 (Site Edition) further supports decoding of the individual memory chip in which the error occurred. The DRAM chip naming (U0...U7) can be adjusted by with config parameter CHIPMAP. See configuration options for details.

The chip ordering convention is illustrated in the images below.

The memory channel, slot and chip number can be identified as below.

Slot numbering convention

For DDR5 motherboards with 4 RAM slots, the most common for desktop motherboards, there is (or was) an loose informal industry convention that slots are numbered in this order with these names. A1, A2, B1, B2. The A and B refer to the channel and the 1 and 2 refer to the slot within that channel. But on some motherboards the slots are labeled just DDR5_1,2,3,4 or A,B,C,D.

With the release of the Intel Ultra 200S CPUs and the 1851 motherboards it seems there is no longer a single standard. Some vendors are A1-A2-B1-B2 while others are B1-B2-A1-A2.

A1-A2-B1-B2	B1-B2-A1-A2
Intel Reference board ASRock ASUS	MSI Gigabyte Biostar

Starting from version 11.1, MemTest86 takes these vendor differences for 1851 motherboards into account.

Supported module types

MemTest86 supports DIMM/chip decoding for installed modules that all have the same type and capacity. The following RAM module types (ie. form factors) are supported:

• UDIMM
• SODIMM

For other form factors (such as soldered RAM in laptops), the module may be represented by the UDIMM graphic in the DIMM results screen. An example of a laptop with 1 soldered module and 1 SODIMM slot is shown below.

Supported platforms

Note: V10 only supports DIMM and Chip decoding for select motherboards, memory and CPU architectures

Currently decoding is available for:

• Motherboards
  • B360-LGA1151
  • Z390-LGA1151
  • B460-LGA1200
  • Z490-LGA1200
  • B560-LGA1200
  • Z590-LGA1200
  • B660-LGA1700
  • Z690-LGA1700
  • B760-LGA1700
  • Z790-LGA1700
  • X570-AM4
  • B650-AM5
  • MTL-S UDIMM 2DPC EVCRB
  • MTL-S UDIMM 1DPC EVCRB
• Processors
  • Intel 8th gen Coffee Lake processors
  • Intel 9th gen Coffee Lake processors
  • Intel 10th gen Comet Lake processors
  • Intel 11th gen Rocket Lake processors
  • Intel 12th gen Alder Lake processors
  • Intel 13th gen Raptor Lake processors
  • Intel 14th gen Raptor Lake processors
  • Intel 14th gen Raptor Lake processors
  • Intel 1st gen Core Ultra Meteor Lake processors
  • Intel 2nd gen Core Ultra Arrow Lake processors
  • AMD Ryzen 3000 series (Matisse)
  • AMD Ryzen 5000 series (Vermeer)
  • AMD Ryzen 7000 series (Raphael)⁽¹⁾
  • AMD Ryzen 9 PRO 7940HS (Phoenix)
• Memory
  • 16/32GB Single/Dual rank x8 DDR5 SDRAM
  • 8GB Single rank x16 DDR5 SDRAM
  • 8/16GB Single/Dual rank x8 DDR4 SDRAM
  • 4GB Single rank x16 DDR4 SDRAM
  • UDIMM/CUDIMM/SODIMM/CSODIMM/CAMM2 form factors

1. Failing chip may not be correctly identified in single rank configurations^