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Matched pairs question


gallowsroad

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Greetings,

 

Just assembled an Asus A8V Deluxe, Amd 64 3200+ based system, with my older Corsair CMX512-2700C2 pair of memory modules installed, dual channel. All is well. I'm intending to upgrade to Corsair TWINX1024-3200C2 and run in dual channel. At some point in the future I may wish to get a second matched pair. Will I run into compatibility issues if I add a second pair of the same model at a later time? I've read here and elsewhere that dual channel with more than a single pair can get tricky.

 

Thanks.

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  • 3 months later...
I have the Asus A8V Deluxe running Twin1024-3200C2 dual channel without any problems. I'm contemplating buying another matched pair, and wanted to know if there are known issues trying to run two sets of matched pairs on this board.

 

Thanks.

There are no "issues" per se as the board will run them. But, what CMC Savage was describing was that you will get a performance drop even though you will have twice as much RAM.

 

When using 4 DIMMs the chipset you have will revert to DDR333 speed. If you CPU can handle it, you can get back up to DDR400+ but, there are no guarantees. This is a chipset limitation. Also, the board will run the memory at a 2T command rate which is slower than 1T. This is another performance hit.

 

So, yes you can run 4 DIMMs. If you don't mind the performance hit it will work just fine. However, you don't see these same limitations with 2 DIMMs (the 2 x 1024mb kit CMC Savage recommended).

 

Mike.

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There are no "issues" per se as the board will run them. But, what CMC Savage was describing was that you will get a performance drop even though you will have twice as much RAM.

 

When using 4 DIMMs the chipset you have will revert to DDR333 speed. If you CPU can handle it, you can get back up to DDR400+ but, there are no guarantees. This is a chipset limitation. Also, the board will run the memory at a 2T command rate which is slower than 1T. This is another performance hit.

 

Mike.

 

I had read with 4 DIMMs manally setting the speed to DDR400 would work. I did not know the command rate would go from 1T to 2T. I just went into the BIOS and did not find a way to set the command rate to anything lower than 2T - there is a "2T Command" setting that offers only Auto, Enabled, and Disabled. Unless I'm missing something ( a real possibility!), I can see no way to set it.

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there is a "2T Command" setting that offers only Auto, Enabled, and Disabled. Unless I'm missing something ( a real possibility!), I can see no way to set it.

 

You probably did miss something, as far as that setting goes. "Auto" means that the 1T/2T command rate depends on the module(s) installed. "Enabled" forces a 2T command rate regardless of the module. "Disabled" forces a 1T command rate.

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You probably did miss something, as far as that setting goes. "Auto" means that the 1T/2T command rate depends on the module(s) installed. "Enabled" forces a 2T command rate regardless of the module. "Disabled" forces a 1T command rate.

 

I tried both Auto and Disabled, and both yield 2T according to Everest. Seems either the modules (Twinx1024-3200C2) won't support it or the mobo hates me. :)

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Actually, the command rate is a property of the memory controller and is rather independant of the modules themselves.

 

However, I don't see why they bother giving you the setting as all Venice core CPU's will force a 2T command rate with that many modules.

 

PLUR

CK

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Assuming you can get 4 dimms to run at 400Mhz (using a Venice); what would be the performance impact of 2T over 1T? Would it be noticeable to the average user in gaming and day to day computing or would it be mostly seen in performance benchmarks?
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Actually, the command rate is a property of the memory controller and is rather independant of the modules themselves.

 

However, I don't see why they bother giving you the setting as all Venice core CPU's will force a 2T command rate with that many modules.

 

PLUR

CK

 

Seems my set up will only run at 2T with just one pair of modules no matter how I alter BIOS settings. I won't be losing anything by adding a second pair, unless there is another way to force 1T with the single set? Will the Venice core always force 2T with only one pair?

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  • Corsair Employees
The command Rate will always set to 2t By default and you can manually try and set it to 1T, however with 4 modules you need to set it to 2T. And yes many have had trouble running 1t Command Rate even with two modules with these new core CPU's.
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The command Rate will always set to 2t By default and you can manually try and set it to 1T, however with 4 modules you need to set it to 2T. And yes many have had trouble running 1t Command Rate even with two modules with these new core CPU's.

 

Thanks for all the replies.

 

I'll go ahead and add the second set - I can use higher capacity, and since it's already running at 2T, there isn't a performance hit.

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  • 2 weeks later...
O.K. please let us know how you make out. But you may need to get a bigger PSU to run 4 modules. They use about 12 watts per module.

 

I got them installed. PSU is not a problem - Seasonic 430W.

 

As many have noted for this board, the bus speed has to be set manually when running two matched pairs. Command rate is 2T, as it was with the single pair, so nothing lost there. Thanks for the replies and help.

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