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Bizarre problem with Corsair TWINX512-3200XL memory.


Explodey

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SUMMARY OF MY MEMORY PROBLEM:

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+ There is an unusual type of incompatibility between my Shuttle AN35N Ultra motherboard and the Corsair TWINX512-3200XL memory I recently installed.

 

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HOW I DISCOVERED THE PROBLEM:

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(1) About four months ago I replaced my 1.33GHz Athlon processor with an Athlon XP 3200+ processor, without experiencing any problems. So, I decided to upgrade my memory to match the FSB speed of the new CPU (400 MHz).

 

(2) About two months ago, I replaced the two 256MB sticks of Corsair PC2400 memory (CM64SD256-2400C2) with two 256MB sticks of low latency Corsair PC3200 memory (TWINX512-3200XL). I tested the system for several hours using the MemTest86 V3.1a utility: no memory errors were reported. I ran the system for several weeks without experiencing any problems.

 

(3) When I went to reinstall Windows, I wanted to ensure that my Shuttle motherboard's BIOS was up-to-date, so I flashed it from version AN35S00L to AN35S00R, and cleared the CMOS.

 

(4) When the PC powered up, it was in "throttled CPU" mode, with the CPU speed listed as 1100MHz and the RAM speed listed as 400MHz. I pressed the Delete key to enter BIOS setup, selected the "Load Fail-Safe Defaults" option, and then selected the "Save & Exit Setup" option.

 

(5) After exiting setup, the screen went blank, and the PC became totally unresponsive. Nothing would appear on the screen after pressing the reset button, after powering down the PC, or even after unplugging the PC to discharge its power supply.

 

(6) Since no other course of action came to mind, I cleared the CMOS again, and then the system would reach the boot screen like it did in Step 4. I went into the BIOS setup and tried different configuration settings, but upon saving and exiting from the BIOS, the system was unresponsive again. I repeatedly cleared the CMOS and tried every permutation of BIOS settings that I could think of, but nothing worked.

 

(7) Since I was having no luck with the BIOS, I began experimenting with the hardware components. I finally discovered that when I took the PC3200 memory sticks out, and put the old PC2400 memory back in, the system then behaved normally, and allowed me to save my BIOS settings to CMOS. Then, much to my surprise, I found out that I could put the PC3200 sticks back in, and the system would boot perfectly.

 

(8) So, to summarize, anytime the CMOS is reset, it cannot be initialized for as long as the Corsair PC3200 memory is installed. However, if PC2400 or PC2700 memory is temporarily installed, the CMOS can then be successfully initialized, and the PC3200 memory can be reinserted.

 

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THE PC CONFIGURATION:

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+ AMD Athlon XP 3200+ Barton, 400MHz FSB

 

+ Corsair TWINX512-3200XL memory (two 256MB, PC3200, latency 2-2-2-5 DIMMs)

http://www.corsairmicro.com/corsair/products/specs/twinx512-3200xl.pdf

 

+ Shuttle AN35N Ultra V1.1 motherboard (NVIDIA nForce2 Ultra 400 chipset)

BIOS versions tested: AN35S00L (05-DEC-2003), AN35S00R (23-AUG-2004)

 

+ eVGA GeForce FX 5700 Personal Cinema graphics card (128MB)

 

+ Turtle Beach Santa Cruz sound card

 

+ SMC 1211TX 10/100 network card

 

+ Adaptec FireConnect 4300 card (3 FireWire ports)

 

+ Thermaltake Silent PurePower W0011 ATX 480W power supply

 

+ None of these components have been overclocked.

 

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EXPERIMENTS THAT I PERFORMED:

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+ I found that if I reset the CMOS, then reset the PC without initializing the CMOS, I could continue to reset the PC and it would not freeze up.

 

+ I determined that the system could not initialize the CMOS, even when just a single PC3200 memory stick was installed. I also found that the problem persisted, whether I used DIMM slot 1, 2 or 3.

 

+ Since I have a pair of AN35N Ultra motherboards, I swapped their BIOS chips to see if the older BIOS had the CMOS initialization problem also. The same problem recurred, so I swapped the BIOS chips back again.

 

+ I tried replacing the NVIDIA graphics card with an older ATI card, and I also removed each of the PCI cards, but these actions made no difference.

 

+ Once the system booted with the CMOS properly initialized, the system ran flawlessly - I ran the MemTest86 diagnostic program for hours, with no memory failures indicated.

 

+ The original memory I had installed was Corsair PC2400 (CM64SD256-2400C2). Also, I recently found out that a stick of Corsair CMX512-2700LL (512MB of PC2700, latency 2-3-2-5) memory from my other PC does not cause the CMOS update problem like the new PC3200 memory does.

 

+ Every now and then, when Windows 2000 is going down for reboot, or if I hit the reset button at an unusual time, the PC will not restart until the PC3200 is removed and slower memory is installed. Then, when I swap the PC3200 back in, everything is fine again.

 

+ I have searched the Corsair memory forum and other forums online, but have not seen anyone else report this particular issue.

 

+ I have purchased at least ten sticks of Corsair memory since I started building PCs, and have never had any problems with it before.

 

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CONCLUSIONS, THEORIES AND QUESTIONS:

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+ It seems conclusive that when the BIOS setup program attempts to write to the CMOS, something goes wrong. It must be partially initializing the CMOS, because if it were not, then resetting the PC should work. NOTE: with any other memory, a "Warning! New setting is updating now, Do not Reset or Shutdown the System" screen appears after BIOS setup is exited, but that screen does not appear with the PC3200 memory.

 

+ Could a modification to the Shuttle BIOS be made, so that when the CMOS is not yet initialized, the memory speed and/or latency timings are throttled at startup? And if this modification were made, is it likely to solve my problem?

 

+ Could the "Plug-n-Frag Auto-Configuration" characteristic of this memory be causing the problem? Here is a summary of Plug-n-Frag taken from http://www.hardwarezone.com/articles/print.php?cid=4&id=1221:

 

"A feature with all low latency Corsair modules is their trademarked Plug-n-Frag. Automatically programming its optimal CAS 2.0, 2-2-5 memory parameters into the BIOS, Plug-n-Frag relieves you of having to enter the BIOS to configure these settings. You may think that this isn't different from setting the memory options in BIOS to 'Auto' and having the Serial Presence Detect (SPD) on the RAM modules automatically configure the settings. Plug-n-Frag is slightly different in the sense that even if you had manually configured the memory options in the BIOS, it will still overwrite them and set the module's own optimal settings. As long as you have a good motherboard, there is practically no chance that the system would not first boot when swapping your old memory for this Corsair TWINX1024-3200XL. In an unfortunate event that your system is not able to sustain such aggressive parameters, you can still set your own settings in the BIOS because the Corsair TWINX1024-3200XL only overwrites the BIOS parameters the first time it is plugged into the system."

 

+ I noticed that high-performance memory from XXXXXXX is described as having "Serial Presence Detect (SPD) with EEPROM". Does this mean that there may be a way to reprogram my Corsair memory with different timings, so that it doesn't cause lockups?

 

+ Is it likely that the nForce2 Ultra 400 chipset has anything to do with this issue?

 

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+ Could the "Plug-n-Frag Auto-Configuration" characteristic of this memory be causing the problem? Here is a summary of Plug-n-Frag taken from http://www.hardwarezone.com/articles/print.php?cid=4&id=1221:

 

In an unfortunate event that your system is not able to sustain such aggressive parameters, you can still set your own settings in the BIOS because the Corsair TWINX1024-3200XL only overwrites the BIOS parameters the first time it is plugged into the system."

Answered your own question (No).

 

 

+ I noticed that high-performance memory from XXXXXXX is described as having "Serial Presence Detect (SPD) with EEPROM". Does this mean that there may be a way to reprogram my Corsair memory with different timings, so that it doesn't cause lockups?

 

All memory has an EEPROM chip that holds the SPD. However, unless you have $30K+ or so equipment (something like that), then you cannot reprogram it.

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+ Could the "Plug-n-Frag Auto-Configuration" characteristic of this memory be causing the problem? Here is a summary of Plug-n-Frag taken from http://www.hardwarezone.com/article...?cid=4&id=1221:

 

In an unfortunate event that your system is not able to sustain such aggressive parameters, you can still set your own settings in the BIOS because the Corsair TWINX1024-3200XL only overwrites the BIOS parameters the first time it is plugged into the system."

Answered your own question (No).

 

Actually, I think that what you quoted supports my theory that the PC3200 problem is due to Plug-N-Frag. Because remember that I only have a problem initializing the CMOS, and not afterwards (assuming that I use a PC2700 DIMM to initialize the CMOS and then swap the PC3200 back in). After all, isn't the CMOS the only way that the PC3200 can know whether or not this is the first time it has been plugged in? So, my theory is that after I clear the CMOS, the PC3200 is going to believe that this is the first time it has been plugged in, and will overwrite the BIOS parameters, whether I want it to or not. How it overrides the BIOS settings I don't know, but that sounds like a questionable thing to do. I wish they had a jumper on the DIMM to select/deselect Plug-N-Frag, or something.

 

All memory has an EEPROM chip that holds the SPD. However, unless you have $30K+ or so equipment (something like that), then you cannot reprogram it.

 

Um, isn't flash memory EEPROM too?

I'm kind of surprised that there's apparently no way to update the SPD parameters while the memory is installed. Or perhaps the memory voltage is too low to support that, or the interface isn't readily available, I have no idea.

 

Thank you for your comments,

Explodey

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  • Corsair Employees

Please make sure that you have the latest BIOS installed on your MB and load optimized default settings and set the following BIOS settings;

TwinX512 or TwinX1024-3200XL

CPU Freq: 200 MHz (400 FSB)

System Performance: User Define

Memory Frequency: 100% or 1:1 or 3:3

Resulting Frequency: 200 MHz (400 FSB)

Memory Timing: Manual

SDRAM CAS Latency: 2T

SDRAM RAS to CAS Delay (tRCD): 2T

SDRAM Row Precharge (tRP): 2T

SDRAM Active to Precharge Delay (tRAS): 5T

DDR Reference Voltage: 2.8 Volts

AGP Voltage: Default *unless you have ATI (9200/9600/9800) or NVIDIA (5200/5700/6600/6800) then 1.6 Volts suggested!*

All other settings are motherboards defaults

Then please test them one at a time with http://www.memtest.org and let’s make sure it's not some other issue! I would run the test for at least 2-3 passes to be sure!

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