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Matching DDR DIMMs


milleron

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I want to upgrade my Asus A8N-SLI Premium rig from 1GB to 2 GB. Unfortunately, my TwinX 1024 3200XLPT modules are no longer available.

TwinX 1024 3200C2 is rated 2-3-3-6 whereas my current 3200XL is rated 2-2-2-5.

If I install TwinX 1024 3200C2 modules in the available slots and set the timings to 2-3-3-6/2T should I expect any problems from mixing the two slightly different sets of DIMMs?

 

Ron

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Yes the system will likely not post, I am sorry but you cannot mix memory with this MB and or platform I would suggest just replacing them with one set of Twinx2048-3200C2 set of modules for best performance.
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Okay, I'm going to speak out of turn here but only because you are doing the same thing I just did but with a different motherboard.

 

I built an ASUS A8V deluxe MB and put TwinX1024-3200XLPT ram in it. (2-2-2-5) Machine has run fine as far as the ram is concerned. Recently I wanted to up the ante from 1gb to 3gb.

 

I bought a set of TwinX2048-3200C2PT which came with a sticker on both sticks that listed ram timings of 3-3-3-8. As you'll see searching Corsairs site, the recommended ram timings are 2-3-3-6.

 

I figure that I'd just let that BIOS sort it out for me and left the ram timing in Auto. NOT!

 

MB booted fine, just didn't see the new 2gb. Tried some different ram timings, 3-3-3-8, NOT!, 2-3-3-6, NOT!

 

Did some research here and discovered that it might actually be something in the BIOS so I flashed the BIOS (rev 1007 to rev 1017) and booted with just the 2gb at 2-3-3-6. Worked fine. Thought about it a bit and decided to try 2-2-2-5 on the TwinX2048-320C2PT. Booted fine and passed memtest with flying colors.

 

Shut it down and added the original TwinX1024-3200XLPT back into the system. Left the ram timings at 2-2-2-5. Systems boots fine and runs stable even overclocked.

 

If you're willing to do a little research and gamble some you too might be successful. YMMV and as you continue to research the info on this site you'll see that what I did should not be working...:laughing:

 

Ken

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Thanks very much for sharing your very interesting experience.

 

I recently upgraded the CPU from an Athlon 64 3500+ with which my RAM ran according to specs -- 2-2-2-5/1T. After upgrading to an X2 4400+, the very same RAM has to run at 2.5-3-3-6/2T. That's not a typo -- 2T. I UPgraded the processor, and it had the effect of grossly degrading my RAM.

 

So, I think I'd never be as lucky as you have been. Rather than buying the C2 and almost surely having to RMA it, I'll probably just follow Ram Guy's suggestion and get a kit of TwinX 2048.

 

To Ram Guy: Why doesn't Corsair any longer sell the 2-2-2-5 3200XL DIMMs?

 

Ron

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I am also running at 2T. Will check later and see if I can boot it all at 1T and let you know what happens.

 

I did my ram 'upgrade' to enhance photoshop performance.

 

With four sticks, you're probably limited to 2T. My rig with two sticks should run perfectly at 1T. It always did with an older, LESS ADVANCED, CPU. It won't any longer. That's ridiculous. It's AMD's fault, not Corsair's.

 

Ron

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3200XLs aren't made anymore because the ICs used for them aren't made anymore.

 

Well, yeah, but I was actually asking why that's the case. I thought it strange that they'd stop making their best performing DDR modules.

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Went back into the BIOS and set 2T to 1T (disable) also set Bank interleave to ON and limited timing to 2:1 (DDR 400).

 

Then downloaded Everest home addition and took a look at the timings.

 

It showed 2T. Ran the Everest benchmarks. Dismal to say the least.

 

Memory Read - 2954 Mb/s

 

Shutdown and removed the TwinX1024-3200XL modules.

 

Everest now reports 1T.

 

Memory Read - 6014 Mb/s Latency 46.4ns

 

So it appears that removing 1/3 of the ram will provide larger performance gains than having the extra 1gb in there.

 

Still have the mem timings at 2-2-2-5. voltage 2.7 and the board is OC'd 4%. (not looking to cook the processor)

 

SiSandra reported the memory bandwidth at 6266 Mb/s and a latency of 66ns.

 

Not sure how to "benchmark" the differences in real world performance using Photoshop CS2. Seems like 2gb of memory running over twice as fast as 3gb of ram puts the 2gb by itself as the clear winner.

 

Am I overlooking something here?

Everest.jpg.0ac41b267be546b96be4435496dc1846.jpg

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Ram Guy,

 

Can you tell me if the difference in memory read speed was caused by the MB going to 2T or if in addition to that it dropped out of dual channel mode?

 

Is there an easy way to tell?

 

And.., for the time being I'll run with only the TwinX2048-3200C2PT modules installed.

 

Thank you.

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First:

Command Rate is not really a memory setting and would be dependent on the make and model of MB and PSU and the specific CPU you have installed. You might look this setting up on http://www.rojakpot.com and get a better explanation.

 

And when you run http://www.memtest.org it will tell you if its running at 128 Bit Mode or 64-Bit Mode, And it will sometimes show you on the first BIOS Post screen as well.

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If you say it's not a memory setting, I certainly believe you (you're RAM GUY :biggrin:), but it's always set in the part of the BIOS that is devoted exclusively to RAM timing, and it does definitely affect performance.

 

Can you tell us what kind of a performance hit 2T command rate causes? If you don't look at memory bandwidth benchmarks to see the difference, at what benchmarks do you look?

 

Ron

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Ron look at the site I gave you and there is no way any one can answer that questions as it's relevant to the system and CPU. However, 1T Command Rate will be faster than 2T in just about any system, but if the system is not stable there is not a lot that can be done in most cases.
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Thanks,

I looked at the BIOS Guide, where Command Rate is listed as "SDRAM Command Rate," but it gives no estimates at all about benchmarking OR at quantifying the performance hit that one takes when moving from 1T to 2T.

 

I can't do any benchmarks myself, because my system will no longer run at 1T since "upgrading" my CPU. I'm thinking that this should be fairly common knowledge amongst the digerati, though. Does anyone know?

 

Ron

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I'll try Memtest again, with the TwinX2048-3200C2PT modules installed and then again with both sets of modules installed (add in the TwinX1024-3200XLPT).

 

I am interested to see why my memory bandwidth dies with both sets of memory installed.

 

Ken

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Alright, I've run memtest again on the TwinX3200-C2PT @2-2-2-5.

 

Memtest lists it as dual channel 128-bit. It also lists the ram as 200 MHz (DDR400) and gives a speed of 1916 MB/s

 

Add in the TwinX3200-XLPT (3gb total) and it calls the ram 100MHz (DDR200) with a speed of 1079 MB/s. Still list the ram as dual channel 128-bit.

 

My purpose in trying to run 3gb of ram is to support photoshop image processing.

 

So now I have to configure a processing test that will tax the system so I can time the difference in performance between the memory bandwidth and the the amount of memory available to CS2 as it relates to image processing.

 

Seems like it should be a no brainer, but then again these MB/s numbers don't match up to what SiSandra or everest home edition are telling me.

 

CPU-Z reports operating at 2T with the 3gb installed even though I have 2T disabled in the BIOS.

 

 

Ken

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