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2 pairs of TWIN2X4096-6400C5DHX wont post !?!


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Hi all,


I've recently finished building my PC, and now that I have an x64 operating system, I thought i'd treat myself to 8GB of ram.


I bought the following:


2 packs of : TWIN2X4096-6400C5DHX - 4GB


The computer or power up would spin up, shutdown and restart.


There was no post beep and no signal to the video card.


After three manual switch off/ restarts, it would boot into life.


I've removed one pair of matched sticks in channel B and now the computer posts and boots fine without a problem.


The bios I am running is 1004, and the settings are all at factory auto default.


I'd like to be able to use all my sticks or alternatively was thinking about buying the 8GB kit : Q2X8G6400C4DHX


I don't really understand about the memory timings, so before I touch anything or change any settings, I thought i'd ask the ramguy! :D:

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If you populate all four DRAM slots, then you are advised to drop the DRAM bandwidth and raise the memory controller voltage.


The only memory Corsair supports in a four DRAM slot population is their Quad kits. This does not mean two dual kits or even worse two dual kits of different versions will not work together, just that you have no recourse to RMA Corsair if they do not work together. If there are problems with the DRAM modules, they are still supported via lifetime warranty, but that is for physical defects and errors in a two stick kit mode. Matched Quad sets are highly binned modules for a four slot population. The Dual sets are tested as a kit, not a Quad and warranted as a dual kit, not a Quad setup. You need to Memtest them as Kits (2 modules, not as a four DRAM slot population). If they fail as a kit or singly, then you have RMA. Keep in mind that there is no support for mixing and matching different versions of DRAM either since different version are of different fabrications and/or manufacturers. They might work, they might not work, but you have no support if they do not work. Thus you are advised to buy all the DRAM at the same time and in this way be more assured of getting the same versions. If you buy online, be sure to specify same versions of the modules and do not expect even then that they will work and again, no support unless you purchase a quad kit.


For a four DRAM slot population of 800Mhz DRAM you are advised to drop the bandwidth to 1066Mhz and raise the NB Voltage +.2v. You can then attempt to recoup some lost bandwidth via the CPU <--> MCH <--> DRAM overclock. Once stability is found, you can then, if you wish, attempt to regain some of the lost bandwidth of the CPU <--> MCH <--> DRAM stream with an overclock. First stability is necessary as some motherboards, even though they state a four slot population, will not work with stability on a four slot population and need to be RMA'd. So, first stabilty, then overclock.


Please research this thread:




There is a limitation of the On Motherboard (Intel) memory controller or On CPU (AMD) and a population of all four banks at the full speed of a two bank run. This limitation is across the board with both AMD and Intel chipset based boards, DDR, DDR2 and DDR3.


Keep in mind that often issues can arise in the longer term even though you have shorter term stability. The issues seldom damage the DRAM unless you raise the DRAM voltage too high. They damage the on CPU (AMD) memory controller which has a harder time keeping up with the demands of a four DRAM slot population being run as fast as a two DRAM slot population. This is why you are advised to perform the DRAM lowering and MCH Voltage raising.


If you need help with specific settings I can set a template for you.


For two channels (four slots) being populated with 6400C5. Set to 667Mhz with 5-5-5-18 2T and 1.9v as well as Northbridge +.2v.

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thanks Derek.


In which case, what if I put two 4GB sticks into a channel?


Would I have the same issues?


I was contemplating purchasing the quad kit as the timings were lower, but I'm now wondering about this.


A template would be of great help.


I've never overclocked before, so it's all new to me!

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In which case, what if I put two 4GB sticks into a channel?


Would I have the same issues?


As long as your hardware can accomodate 4GB modules (check your manual or MOBO spex) then the density is not the issue. Your limitation is the load of 4 modules on the memory controller.


Please read AN806 for more details on this: http://www.corsairmemory.com/appnotes/default.aspx

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I see.


The motherboard documentation specs state that it can support 16GB, which at the moment is obviously not the case, but this is the main reason I bought it! otherwise, I would have stuck to an intel branded motherboard.


I think for my next build i'm going to leave Taiwanese stuff behind and just follow my gut which has always been to look to intel or Supermicro.


So if I were to buy the Quad kit, how would I work around the issues i'm currently facing?

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Yes, 2 X 4GB would be best. Your board supports this configuration but it's not easy to find 4GB modules.

Download memtest from--->

and extract the ISO image. Burn the ISO image to an CD-ROM disk.

Download CPU-z from

Enter your BIOS, Load Setup Defaults, Save Setup Defaults and set to these values:

AI Overclock Tweaker

Configure System Performance Settings

Ai Overclock Tuner = Manual
CPU Ratio Setting = 8.5
FSB Frequency = 333
PCI-E Frequency = 100
FSB Strap to Northbridge = 333
DRAM Frequency = Manual
DRAM CLK Skew on Channel A1 = Auto
DRAM CLK Skew on Channel A2 = Auto
DRAM CLK Skew on Channel B1 = Auto
DRAM CLK Skew on Channel B2 = Auto

DRAM Timing Control = Manual
DRAM Frequency = DDR2-667
DRAM Command Rate = 2N
DRAM Timing Control = Manual
CAS# Latency =  5
RAS# to CAS# Delay = 5
RAS# PRE Time = 5
RAS# ACT Time = 15
Row Refresh Cycle Time (tRFC) = 55 
All Else to Auto

DRAM Static Read Control = Auto
DRAM Read Training = Auto
Mem. OC Charger = Auto
AI Transaction Booster = Auto

CPU Voltage = Auto
CPU PLL Voltage = Auto
FSB Termination Voltage = Auto
DRAM Voltage = 1.9v
NB Voltage = 1.33v
SB Voltage = Auto
PCI-E SATA Voltage = Auto

Loadline Calibration = Auto
CPU Spread Spectrum = Disabled
PCIE Spread Spectrum = Disabled

Clock Over-Charging Voltage = Auto
Load Line Calibration = Auto
CPU GTL Voltage Reference = Auto
NB GTL Voltage Reference = Auto

Memory Remap - Enabled

Legacy USB = Disabled (For Memtest, Enabled After Memtest)

Run Memtest for two full passes. When assured of stable DRAM, then enter Windows and Run CPU-z and post screenshots of CPU-z's CPU, Memory and SPD tabs.

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thanks Derek.


Today i've ordered the Quad C4 kit specified as the preferred choice for my system : Q2X8G6400C4DHX


After reading yours and the Ram guys' thoughts on the matter, i feel that I may as well do it right.


Would the settings you've given me remain the same apart from the cas and voltage change to 2.1v ?


I really do appreciate your help.:o:

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Those settings are correct except you can run them at DDR800 with 4 up, but only with the Q2X8G6400C4DHX.


Thanks Ram Guy,


So I can ammend to the following:


DRAM Timing Control = Manual

DRAM Frequency = DDR2-800

DRAM Command Rate = 2N

DRAM Timing Control = Manual

CAS# Latency = 4

RAS# to CAS# Delay = 4

RAS# PRE Time = 4

RAS# ACT Time = 12

Row Refresh Cycle Time (tRFC) = 55

All Else to Auto


DRAM Voltage 2.1


I am right in this? - the memory checker says that the voltage is 2.1

and yes, the Q2 kit that you've mentioned, is the one i've ordered.

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Derek, ramGuy,


I've fitted the quad kit, and updated to the latest BIOS for the board, 1806.


Many of the settings are now auto and cannot be alterred on the bios, such as the NB Voltage, but I changed what I could and did a memtest without hiccup.


The CPU-z screenshots are as follows:





Memory Tab






Hopefully all is well!


Many thanks once again both of you for all your help.

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