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4gb slower than 2gb


JerseyBiker

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I have Gateway computer that I have owned for close to 3 years. I have updated most of the major components over time. My computer has an Intel DG965OT motherboard and I have the latest firmware and drivers installed. I have a Intel E6700 Core 2 Duo processor.

 

I had 2gb of Corsair XMS2 ram chips with Windows Vista 32bit and everything ran fine. Recently I installed Windows 7 64bit and it worked fine with the same 2gb of ram. I purchased another pair of the EXACT SAME Corsair ram chips purchased from the same place, Amazon, as the first pair. After installing the second pair of Corsair chips my system is very slow and unstable. When I remove either pair of RAM chips my system runs great. I tried running the RAM at both 667 and 800. 667 seems a little more stable but still significantly slower then when I use just 2 chips. Can someone please tell me why 4gb of RAM would run slower than 2? Thanks.

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I have Gateway computer that I have owned for close to 3 years. I have updated most of the major components over time. My computer has an Intel DG965OT motherboard and I have the latest firmware and drivers installed. I have a Intel E6700 Core 2 Duo processor.

 

I had 2gb of Corsair XMS2 ram chips with Windows Vista 32bit and everything ran fine. Recently I installed Windows 7 64bit and it worked fine with the same 2gb of ram. I purchased another pair of the EXACT SAME Corsair ram chips purchased from the same place, Amazon, as the first pair. After installing the second pair of Corsair chips my system is very slow and unstable. When I remove either pair of RAM chips my system runs great. I tried running the RAM at both 667 and 800. 667 seems a little more stable but still significantly slower then when I use just 2 chips. Can someone please tell me why 4gb of RAM would run slower than 2? Thanks.

 

This is due to the extra loading on the G965 chipset's memory controller when you have more than two ranks of memory per channel installed. Normally, the memory controller's command rate on Intel platforms with only two ranks per channel is set to AUTO where the controller may use 1T or 2T depending on the demands of the software and processor (at that setting, the memory controller will run at a 1T command rate most of the time). But with four ranks of memory per channel installed, the G965's memory controller will force the command rate to be fixed at 2T for enhanced stability. Unfortunately, setting the higher-numbered command rate will affect the performance of the memory (effective bandwidth will be reduced).

 

Also, your system ran a bit unstable with all four DIMM slots filled even at the memory's reduced speed because you were actually mixing different revisions of the same memory model. The newer kit you bought is likely of a different version number than your existing kit - and the two kits actually use different IC chips with electrical characteristics that are different enough to cause stability issues even at lower memory speeds (or put it this way, the two kits don't quite play nice with one another).

 

And there is no way at all whatsoever to manually set the command rate on the DG965OT motherboard or on any other Intel-brand motherboard outside of the Extreme Series. (IIRC the DG965OT was part of the company's Media Series of motherboards - a "mainstream" series that is now largely populated by several various H55 and P55 chipset motherboards for LGA1156 i3/i5/i7 processors.) It's either on AUTO with one or two ranks per channel of memory installed, or on 2T with more than two ranks per channel installed.

 

As a result, I would heed the recommendation of the RAM GUY when it comes to memory: It's always better to buy the greatest amount of memory on the fewest number of modules within the limitations set by the memory controller if you're planning to run a 64-bit Windows operating system. For the DG965OT, it's better to get one TWIN2X4096-6400C5 series kit than two TWIN2X2048 kits of any speed. (Be absolutely sure to get the 6400C5, not the 6400C4 since the latter requires a DIMM voltage of 2.1V whereas the 6400C5 uses 1.8V.) One TWIN2X2048 kit would suffice if you're going to stick with 32-bit Windows.

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This is due to the extra loading on the G965 chipset's memory controller when you have more than two ranks of memory per channel installed. Normally, the memory controller's command rate on Intel platforms with only two ranks per channel is set to AUTO where the controller may use 1T or 2T depending on the demands of the software and processor (at that setting, the memory controller will run at a 1T command rate most of the time). But with four ranks of memory per channel installed, the G965's memory controller will force the command rate to be fixed at 2T for enhanced stability

 

Wow. That was fast and so detailed. I really appreciate your assistance. I wish I had come here sooner. I did purchase the second pair of Corsair RAM a couple of years after the first pair so I guess you are right there probably is a difference. I'm going to purchase a pair of 2gb memory as you suggested. I'll let you know how things work out. Thank you very much.

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For the DG965OT, it's better to get one TWIN2X4096-6400C5 series kit than two TWIN2X2048 kits of any speed. (Be absolutely sure to get the 6400C5, not the 6400C4 since the latter requires a DIMM voltage of 2.1V whereas the 6400C5 uses 1.8V.) One TWIN2X2048 kit would suffice if you're going to stick with 32-bit Windows.

 

I purchased and installed 4gb of the latest version of the TWIN2X4096-6400C5C memory as you suggested. That did the trick. Everything is working fine now. Thank you very much.

 

~eddie

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