Pixelmonk
2015-08-15, 04:43:39
Memtest86 (6.1) (http://www.memtest86.com/) bietet einen neuen Rowhammer-test.
Scheinbar produzieren viele Speicher (hauptsächlich DDR3) im Test Fehler. Mein Speicher (G.Skill F3-12800CL9-GBRL @2133CL11, 1.4volt) hat über hundert Fehler im Test produziert, obwohl er alle anderen Tests (auch in Windows) bestanden hat und der immer Rechner stabil lief. Selbst eine extreme Erhöhung der Haupt-timings hat keine Verbesserung gebracht.
Geholfen hat letztendlich die Reduktion des Row Refresh-interval (tREFI) auf 4000. Andere Leute berichten dass sie tREFI auf 3500 reduzieren mussten. Durch die Reduktion von tREFI reduziert sich etwas die Bandbreite. Durch die gleichzeitige Reduktion von tRFC auf 200 konnte ich die Bandbreiten-reduktion fast neutralisieren.
Why am I only getting errors during Test 13 Hammer Test?
The Hammer Test is designed to detect RAM modules that are susceptible to disturbance errors caused by charge leakage. This phenomenon is characterized in the research paper Flipping Bits in Memory Without Accessing Them: An Experimental Study of DRAM Disturbance Errors by Yoongu Kim et al. According to the research, a significant number of RAM modules manufacted 2010 or newer are affected by this defect. In simple terms, susceptible RAM modules can be subjected to disturbance errors when repeatedly accessing addresses in the same memory bank but different rows in a short period of time. Errors occur when the repeated access causes charge loss in a memory cell, before the cell contents can be refreshed at the next DRAM refresh interval.
The errors detected during Test 13, albeit exposed only in extreme memory access cases, are most certainly real errors. During typical home PC usage (eg. web browsing, word processing, etc.), it is less likely that the memory usage pattern will fall into the extreme case that make it vulnerable to disturbance errors. It may be of greater concern if you were running highly sensitive equipment such as medical equipment, aircraft control systems, or bank database servers. It is impossible to predict with any accuracy if these errors will occur in real life applications. One would need to do a major scientific study of 1000 of computers and their usage patterns, then do a forensic analysis of each application to study how it makes use of the RAM while it executes. To date, we have only seen 1-bit errors as a result of running the Hammer Test.
There are several actions that can be taken when you discover that your RAM modules are vulnerable to disturbance errors:
Do nothing
Replace the RAM modules
Use RAM modules with error-checking capabilities (eg. ECC)
Depending on your willingness to live with the possibility of these errors manifesting itself as real problems, you may choose to do nothing and accept the risk. For home use you may be willing to live with the errors. In our experience, we have several machines that have been stable for home/office use despite experiencing errors in the Hammer Test.
You may also choose to replace the RAM with modules that have been known to pass the Hammer Test. Choose RAM modules of different brand/model as it is likely that the RAM modules with the same model would still fail the Hammer test.
For sensitive equipment requiring high availability/reliability, you'd replace the RAM without question and would probably switch to RAM with error correction such as ECC RAM. Even a 1-bit error can result in catastrophic consequences for say, a bank account balance. Note that not all motherboards support ECC memory, so consult the motherbaord specifications before purchasing ECC RAM.
http://www.memtest86.com/troubleshooting.htm
Scheinbar produzieren viele Speicher (hauptsächlich DDR3) im Test Fehler. Mein Speicher (G.Skill F3-12800CL9-GBRL @2133CL11, 1.4volt) hat über hundert Fehler im Test produziert, obwohl er alle anderen Tests (auch in Windows) bestanden hat und der immer Rechner stabil lief. Selbst eine extreme Erhöhung der Haupt-timings hat keine Verbesserung gebracht.
Geholfen hat letztendlich die Reduktion des Row Refresh-interval (tREFI) auf 4000. Andere Leute berichten dass sie tREFI auf 3500 reduzieren mussten. Durch die Reduktion von tREFI reduziert sich etwas die Bandbreite. Durch die gleichzeitige Reduktion von tRFC auf 200 konnte ich die Bandbreiten-reduktion fast neutralisieren.
Why am I only getting errors during Test 13 Hammer Test?
The Hammer Test is designed to detect RAM modules that are susceptible to disturbance errors caused by charge leakage. This phenomenon is characterized in the research paper Flipping Bits in Memory Without Accessing Them: An Experimental Study of DRAM Disturbance Errors by Yoongu Kim et al. According to the research, a significant number of RAM modules manufacted 2010 or newer are affected by this defect. In simple terms, susceptible RAM modules can be subjected to disturbance errors when repeatedly accessing addresses in the same memory bank but different rows in a short period of time. Errors occur when the repeated access causes charge loss in a memory cell, before the cell contents can be refreshed at the next DRAM refresh interval.
The errors detected during Test 13, albeit exposed only in extreme memory access cases, are most certainly real errors. During typical home PC usage (eg. web browsing, word processing, etc.), it is less likely that the memory usage pattern will fall into the extreme case that make it vulnerable to disturbance errors. It may be of greater concern if you were running highly sensitive equipment such as medical equipment, aircraft control systems, or bank database servers. It is impossible to predict with any accuracy if these errors will occur in real life applications. One would need to do a major scientific study of 1000 of computers and their usage patterns, then do a forensic analysis of each application to study how it makes use of the RAM while it executes. To date, we have only seen 1-bit errors as a result of running the Hammer Test.
There are several actions that can be taken when you discover that your RAM modules are vulnerable to disturbance errors:
Do nothing
Replace the RAM modules
Use RAM modules with error-checking capabilities (eg. ECC)
Depending on your willingness to live with the possibility of these errors manifesting itself as real problems, you may choose to do nothing and accept the risk. For home use you may be willing to live with the errors. In our experience, we have several machines that have been stable for home/office use despite experiencing errors in the Hammer Test.
You may also choose to replace the RAM with modules that have been known to pass the Hammer Test. Choose RAM modules of different brand/model as it is likely that the RAM modules with the same model would still fail the Hammer test.
For sensitive equipment requiring high availability/reliability, you'd replace the RAM without question and would probably switch to RAM with error correction such as ECC RAM. Even a 1-bit error can result in catastrophic consequences for say, a bank account balance. Note that not all motherboards support ECC memory, so consult the motherbaord specifications before purchasing ECC RAM.
http://www.memtest86.com/troubleshooting.htm