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Why Does My System Hang When I Use 4 DIMMs, but not with only 2 DIMMS?


SkykingUSA

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I just bought 2 of these: TWIN2X4096-6400C4DHX for a total of 8GB. My system specs are in the pull down, and are up to date.

 

My problem is that the system is only stable when I have 2 DIMMS installed, not when I have 4 installed.

 

I have tested each pair using memtest86+ from memtest.org and no errors are detected. I also updated my BIOS to the latest version for my board from aBit and reset the cmos, then applied the default settings. Still cannot get more than 2 DIMMS running without the system hanging within 10-20 seconds after powering on. To be more specific, I turn on the system, watch it POST, and sometimes it makes it through the post and Windows gives me an error message when it tries to boot saying that the hardware has changed and I should check with the manufacturer, and other times, it just stops responding before the POST finishes - at random spots each time. After it hangs, I have to reset or power off to get it back, or if I leave it in the hung state, it will power itself off in about 30 seconds. Again, this is only with 4 DIMMS installed, 2 DIMMS installed are fine - everything is stable.

 

Currently, as I run 2 DIMMS (4GB total) the BIOS has the following settings which I made sure to set manually like I found in another post in this forum:

 

- Memory is running at 800MHz

- Timing is set to 4-4-4-12 2T

- DDR2 Voltage on the board defaulted to 1.85V, but I set it to 2.1V and now it is at 2.0V (Windows would blue screen every now and then when I left it at 1.85V)

 

I just reinstalled the OS fresh after buying this memory, so the system is quite "clean".

 

Any ideas for me to try so I can make use of my full 8GB of memory that I purchased? I have never had problems adding memory to a system before, but then again, I have never tried going over 4GB before either.

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I bought 2 packs of TWIN2X4096-6400C4DHX. Is it important that I pair them up when installing, or does that really matter any more?

 

Also, if I install only 2 DIMMS, I'm not sure which of the 4 DIMM slots I should put them in for my Motherboard (the manual is really not great, and the support site is not easy for me to navigate either). My BIOS says the memory is running at 800MHz, but CPU-Z says "Channels #" on the Memory tab is "Single". Should I trust the BIOS or should I trust CPU-Z?

 

http://www.skykingtech.com/CPUZ01.JPG

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I bought 2 packs of TWIN2X4096-6400C4DHX. Is it important that I pair them up when installing, or does that really matter any more?

 

Also, if I install only 2 DIMMS, I'm not sure which of the 4 DIMM slots I should put them in for my Motherboard (the manual is really not great, and the support site is not easy for me to navigate either). My BIOS says the memory is running at 800MHz, but CPU-Z says "Channels #" on the Memory tab is "Single". Should I trust the BIOS or should I trust CPU-Z?

 

The memory must be paired to enable Dual Channel Mode. Look at the SPD tabs and you will see if they fit. You are running at 400 X 2 (DDR) = 800Mhz. But you need to set the DRAM in matched pairs to enable Dual Channel Mode.

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You are advised to drop the bandwidth when using two kits. It is not advised to run a two kit (four module) solution as fast as a one kit (two module) solution. Have you memtested singly? Set the CPU to 333Mhz and the DRAM to 667 4-4-4-12 2T and 2.1v and Memtest the modules singly. First I would perform a hard reset of your system.

  1. Shut the system down
  2. Remove the power cord
  3. Remove the CMOS Battery
  4. Set the CMOS_CLR Jumper to On
  5. Press the power button for 10 seconds
  6. Let sit for 10 minutes
  7. Set the CMOS_CLR Jumper to Off
  8. Insert the CMOS Battery
  9. Insert the Power Cord
  10. Restart the system
  11. Enter the BIOS
  12. Load Default Settings
  13. Save Default Settings and Exit

Download Memtest86+ V2.11 from--->

Download CPU-z from
.

SoftMenu Setup
SLI-Ready Memory = Disable
CPU Operating Speed = 1333 (333)
Memory Operating Speed 1333 (667)

Memory Timing Setting

CL Cas Latency = 4
tRCD = 4
tRP = 4
tRAS = 12
Command Per Clock (CMD) = 2T

Advanced Memory Settings

tRRD = Auto
tRC = Auto
tWR = Auto
tWTR= Auto
tREF = Auto 
tRD = Auto
tRFC = 60

Async Latency = Auto
CPU Spread Spectrum: Disabled
PCIE Spread Spectrum: Disabled 
MCP PCIE Spread Spectrum: Disabled 
SATA Spread Spectrum: Disabled
LDT Spread Spectrum: Disabled

CPU Features

Thermal Control: Enabled
Limit CPUID MaxVal: Disabled
Execute Disable Bit: Enabled
Virtualization Technology: Enabled
Frequency Unlimit = Enabled
Core Multi-Processing = Enabled

PCIEX16_1 Frequency (Mhz): 101
PCIEX16_2 Frequency (Mhz): 101
PCIEX16_3 Frequency (Mhz): 101
SPP<->MCP Ref Clock, Mhz: 201

Voltages

CPU Core = Auto
CPU FSB = Auto
Memory = 2.1v
NForce SPP = 1.4v
NForce MCP = 1.55v
HT NForce SPP <--> MCP = 1.50v

Shut the system down. Insert one stick in slot one (closest to the CPU) and boot to the Memtest CD. Run Memtest for two full passes. Shut the system down. Remove the first stick and insert it in slot two. Repeat memtest. Shut the system down. Remove the first stick and insert it into slot three and repeat memtest. Do the same for the last slot. You have now tested one stick and all four slots. Shut the system down and remove the first stick. Insert the second stick in slot one. Retest. Shut the system down and remove the second stick and insert the third stick in slot one. Repeat Memtest. Do the same with the last stick. You have now tested all four sticks in Single Channel Mode.

 

Now test for the Dual Channel Mode function of the memory controller. Insert a stick in slot one and three and memtest. Remove the set and insert the second set in slot two and four and memtest.

 

Finally, insert a stick in slot one and slot three, a stick in slot two and slot four and repeat Memtest. If Stable enter Windows and post screenshots of CPU-z's CPU, Memory and SPD tabs.

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I bought 2 packs of TWIN2X4096-6400C4DHX. Is it important that I pair them up when installing, or does that really matter any more?

 

Also, if I install only 2 DIMMS, I'm not sure which of the 4 DIMM slots I should put them in for my Motherboard (the manual is really not great, and the support site is not easy for me to navigate either). My BIOS says the memory is running at 800MHz, but CPU-Z says "Channels #" on the Memory tab is "Single". Should I trust the BIOS or should I trust CPU-Z?

 

Try different combinations of slots. That board is set up for dual channel memory configurations.

 

As far as the modules, check the numbering on the stickers. If all of your modules are the same version or revision, then you can pair them any way you like. However, if you have different revisions, you should try to put the matched pairs on the same channel.

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Try different combinations of slots. That board is set up for dual channel memory configurations.

 

As far as the modules, check the numbering on the stickers. If all of your modules are the same version or revision, then you can pair them any way you like. However, if you have different revisions, you should try to put the matched pairs on the same channel.

 

Thanks for this information, but how do I know if my memory is actually operating in dual channel mode? Is CPU-Z a trustworthy tool for this information? Man, that would really suck if I thought I was running in dual channel mode for the past year and a half (with my old Corsair DIMMS) and I was actually not. Haha. I guess if I didn't have a problem, it's no big deal but I like to get what I can out of something aside from overclocking it.

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DerekT: Thank you so much for the instructions! My problem seems to be solved now. As I write this, my system is running with all 4 DIMMS in for a total of 8GB in Vista x64 SP1. Time will tell regarding the stability, and I am still thinking of trying to increase the speed of the DIMMs to see what happens, but at least it seems to be stable again, which is really what I wanted in the first place.

 

Let me tell you what I did. Basically, I followed your steps, just not so comprehensive. I had reset the cmos a couple of days ago, so I didn't re-do that.

 

I made sure that the BIOS was using default speeds and memory timings at first, then I set the following:

  • I had to enable the SLI-Ready Memory feature, otherwise I could not change my other memory settings
  • made sure my FSB was at 3333
  • made sure my memory was at 667
  • made sure my mem timings were 4-4-4-12-2T
  • left all other memory settings to Auto
  • had no spread spectrum settings to set in my BIOS
  • my CPU features were already as you indicated
  • left my PCIe and SPP settings to default, which are 100,100,100,200
  • I was afraid to change voltages because I didn't know what was safe, and couldn't find the same descriptions in my BIOS, so all I changed was the DDR2 voltage to 2.1V - left others at default BIOS settings

 

I then tested two DIMMs at a time in slots 1 & 2, then 1 & 3, then 2 & 4, and I used both pairs of DIMMs. All the DIMMs and slots passed 1 memtest pass with no errors. Then, I finally tried all 4 slots full, and to my surprise, it went through a whole pass with no errors!

 

Out of all the testing described above, there are basically 2 things that are different than what I tried previously:

 

  • The way I paired up the memory in the slots, and
  • The speed of the memory (667 MHz versus 800 MHz previously)

 

I am a little embarrassed to say that I was previously not running in dual channel mode. I had my old pair in slots 1 and 2, when they should have been in slots 1 and 3, which was confirmed by CPU-Z and also now by my POST screen. Geez, I hate that. Sigh. But I'm glad I know now.

 

Also, I had not tried running the memory at anything less than 800 MHz before. So, between these two things, I figure one of them is the reason it now works. I did check the versions on my 4 modules (they are all version 1.1), so based on a previous post in this thread, they should all work together, so my problem may not have been with how I installed them, but with the memory speed. Maybe the system just cannot handle 8GB among 4 DIMMs at 800MHz.

 

In any case, I will probably leave the system running as is for now at 667 MHz for a day or two to see how stable it is, and then set the speed back to 800 MHz to see what happens. If it hangs again, at least I can always set it back to a stable 667. That will also narrow the two remaining variables and will likely tell me if the speed was the culprit or the order in which I installed the DIMMs.

 

Either way, thanks to everyone in this thread who posted ideas and especially to DerekT for all the help. I am very relieved and glad that this Corsair forum is here to help guys like me who have a little knowledge, but lack the time to do a ton of research and learn more about the finer details of memory and computer issues!

 

I almost forgot - here are my 3 CPU-Z screenshots you asked for. My processor Core Speed must be throttling itself because it jumps up to 3GHz and x9 depending what I am doing. If I drag a window around the screen or do something more cpu intensive than just browse this forum, it goes to 3GHz. Also, on the SPD tab, all 4 slots have exactly the same information. If there is anything these screens tell you that I should know about it, I'm all ears. Thanks again!

 

http://www.skykingtech.com/mem/cpu.jpg

http://www.skykingtech.com/mem/memory.jpg

http://www.skykingtech.com/mem/spd.jpg

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A small increase in voltage to the memory controller may help you get to DDR800+ on the memory. You can adjust this in the mGURU utility.

 

Glad to hear you got it stable now.

 

Would that be the DDR2 voltage? If so, I've already got it at the max rating for the DIMMs which is 2.1V. I do not want to push it past its guaranteed voltage.

 

System is still stable by the way. It has been running non stop for over 24 hours now. I used it all day today for work using VMware, etc. No problems! :laughing:

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