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Intel D975XBX2 w/ 3GB XMS2-6400C4 ?


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Hello, and good morning, good afternoon, good evening.


A few months back, I bought a matched pair of TWIN2X2048-6400C4 from Newegg.com. About a month after I built my system (see system specs), one of the modules went bad. As I know that the RMA process can take a long time, and because I needed this machine, I just waited until I had enough money to buy a set of TWIN2X1024-6400C4 to use while I sent the 2GB kit back. (The reason I chose a 1GB kit over another 2GB kit is that I only plan to use Windows XP Pro x32, and IIRC, XPx32 can only address 3 GB of memory. So buying another GB would have really just been a waste.)




Just FYI, for those who might also be wondering about the RMA times:


RMA Issued On: 10/12/2007

Package was sent from SW Florida on Monday, October 15th, 2007.

Package arrived at the Corsair warehouse on Monday, October 22nd.

Reported received on Wednesday, October 24, 2007.

Defective Parts Received on: 10/24/2007

* NOTE: it may take up to 24 hours for this date to be updated after arrival at Corsair

Part Number Received: TWIN2X2048-6400C4

Quantity Received: 1

RMA Replacement Parts Ship Date: 10/31/2007

Replacement Part Number: TWIN2X2048-6400C4 G

Replacement Part Quantity: 1

Replacement Shipping Method: UPS 3 Day Select


... now, the RMA, once shipped, was not supposed to get here until Monday, November 5, 2007, however, I actually received it the previous Friday, November 2, 2007. So, kudos on the return shipping time. I was worried about the processing time, since a week is a little outside of 48-72 hours, but I received the correct parts, and had some extra memory on hand just in case this sort of thing happened, so no complaints here.




I had been running the 1GB pair at 4-4-4-12 at 2.12V, at 667 MHz, with a 333 reference bus speed. I also upped the FSB base freq. on the CPU from 266MHz (1066MHz) to 333MHz (1333MHz), effectively raising the CPU speed to 3.0 GHz, and creating a 1:1 FSB:DRAM ratio. (The CPU multiplier I believe is locked at 9x.) Everything had been working perfectly at this setting. The voltages I had set are as follows:


CPU V: 1.3250

CPU FSB V: 1.250

MCH/ICH V: 1.525


CPU-Z is telling me that currently, my CPU V is: 1.238V


Now that I have received the 2 GB kit, the first thing I did was MemTest overnight, at the above settings (I took out the 1GB kit, and put the 2GB kit in its place.) No errors.


So, now that my new memory has no errors, I placed all 3 GB into the computer, with the above settings, as follows:


Channel A, DIMM 0: CM2X1024-6400C4

Channel A, DIMM 1: CM2X512-6400C4

Channel B, DIMM 0: CM2X1024-6400C4

Channel B, DIMM 1: CM2X512-6400C4


... the computer failed to POST. I had to switch the jumper to Maintenance mode, and reset the timings back to SPD to get it to POST again.


After saving my customized settings as defaults, I upgraded to the latest BIOS as of today's date: BX97520J.86A.2802.2007.1024.1947, version 2802, released October 24, 2007, at 7:47 PM. This did not help.


So, I'm back at defaults, 2.4 GHz, 266MHz FSB (1066 MHZ effective).


I believe the memory is running at SPD (5-5-5-18), at 800MHz. (Trc:21)


The manufacturing date listed by CPU-Z is Week 23, Year 06, for all 4 modules.


According to CPU-Z, the Timings table is: 400MHz, 4-4-4-12 (Trc:22, Command rate: 2T) for all 4 modules.


So my FSB:DRAM is now 2:3.


I have been reading about the D975XBX2 boards, and having 4 slots populated, and that you recommend having the memory set at 667MHz, 2.1(2)v. I don't know much about overclocking / memory settings, however, I cannot seem to get this memory to run at 4-4-4-12, at any speed. The only thing I have changed in the BIOS so far, after defaults have been set, is the voltage to 2.12V. I believe everything else is stock.


So, to conclude, I believe I have the following questions:


Am I doing everything right so far?


What needs to be changed to get these modules running at 667 MHz at 4-4-4-12? Is that even possible? Should they be run at 800MHz?


(If this is not optimal, what would the optimal setup here?)


I have heard that it is better to have 2 sticks of memory rather than 4, because of loading on the memory controller. Would my performance be better with the (2) 1GB sticks as opposed to having all 4 slots populated?


Also, as an aside, I checked here:



for the ICs used in my modules. I found:









for the 1024 sticks, but I was unable to find anything on the 512 sticks. Did I miss something? If they are not posted, could you find out? This would be much appreciated.



Another quick question I had was:


If the memory modules are rated at 4-4-4-12, why is the SPD set to 5-5-5-18? It just seems odd to me... (edit, added 11/3/07 2108 EDT.)



I scanned my memory modules, to get all of the information on each chip. The image is attached.


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You might have to bite the bullet and accept that the board will not accept the extra 1GB of DRAM with the 4-4-4-12 timings. Remember that of all the Core 2 boards, the i975 is the oldest chipset with the most finicky memory controller.


You might have to accept a limitation of this board of yours.

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I would also like to hear RamGuy's (and Wired's) take on this situation.
Of course :)


Which situation would yield more performance:


2 GB @ 4-4-4-12,




3 GB @ 5-5-5-18...




I'm not sure about the speed (MHz) yet.


It depends on your use of the system. In most normal use, you will not be making use of the extra GB anyway so if you are not making use of it in the running of a program, then the 2GB @ 4-4-4-12 will be faster. If, however, you are making use of programs that do well with more DRAM (Photoshop and very large rendering of graphics with many backward steps, Autocad 3D, Maya 3D, etc) then the extra GB means that there will be less swapping to the Hard Drive and the DRAM is always much faster than the Hard drive regardless of the timings set. So it really depends on the use you make of your system. I find that with my system, 2GB is more than enough and this is even in games such as Crysis Demo, Bioshock, etc. My computer is a communication device, an entertainment device and a repository for data. So I find no need to move to 4GB at this time. Certainly I have more than enough money to throw in 4 or 8 GB if there was a difference.


So, you need to look at the use you make of your system and relate that to the population of memory in your system. As well, you might well have to overclock the Northbridge a bit to get these sticks to work. If you raise the CPU FSB a bit, then you concurrently raise the MCH/Northbridge speed as well. This, along with the 0.5v increase at the MCH might well be enough to find a stability.

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If you are using 4 modules in this board then you will need to set the memory frequency down to 667MHz. You may be able to run the memory faster, however you would most likely need to overclock the CPU and/or motherboard. I would recommend that you test each module individually with memtest at 800MHz 4-4-4-12, at 2.1 volts and make sure that all the modules are operating correctly individually. If all the modules pass at their tested settings, then it may be a limitation of the memory controller, when populating all 4 DIMM slots.
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