Dual Channel DDR matched 1GB (1x512/1x512) plus another 512mb stick? Bad idea?

SmiGDigSmiGDig Albany, NY
edited March 2006 in Hardware
Hey guys:

I just bought a set of Corsair XMS CMX512-3200C2 (2x 512MB = 1GB) and have one each in DIMM slots 1 and 3 on my NF7-S 2.0.

Would it be bad to mix in channel 2 with another stick, CMX512-3200XL that was in my system alone before this? It is able to perform at the same specs as these are running currently so stability as far as that aspect isn't an issue?

If I add this stick I'd have: (512MB on one channel - 1GB on the other)
DIMM 1 = CMX512-3200C2
DIMM2 = CMX512-3200XL
DIMM3 = CMX512-3200C2

I'm just looking to see if it is dangerous to have unbalanced channels and all 3 DIMMs full.

Thanks,
Adam

Comments

  • madmatmadmat
    edited March 2006
    You'll shut off dual channel and the XL is, I think, lower latency ram than the other ram so it'll be resigned to running looser timings since the bios will asign timings based on the slowest (loosest) ram. Other than that it should work fine although I think it will default to PC2700 speeds with 3 big DIMMs in there if I'm not mistaken. That just means if you have a proc with 200FSB (or are oc'ing to that FSB) the ram will be running with a divider.
  • muddocktormuddocktor
    edited March 2006
    Like Matt said, you lose dual channel operation of your ram, but that's not a big deal with an AXP system anyways, since they don't need high bandwidth to perform well. As for it stepping the memory frequency to PC2700, I don't know as I've never run 3 dimms in a NF2 system. But your can always try fiddling around with memory speeds and timings manually in bios, since the NF7S is a very tunable board. You might try running memtest86 after messing with the bios settings on ram speed and timings to check for ram stability.
  • lemonlimelemonlime Canada Member
    edited March 2006
    Yep, I totally agree with Mudd.. There is little to no performance loss moving to single channel on an NF2. It is definitely worth a try, but yes, run some thorough stability testing once you add the third dimm. It may default to 2T timings, but I don't think it will drop to PC2700 with an AXP (the Revision CG/D A64s do that though).

    Let us know how it goes :thumbsup:
  • SmiGDigSmiGDig Albany, NY
    edited March 2006
    Hey guys:

    I'm gonna give it a whirl later this evening.

    Surprisingly, these two sticks aren't any slower than the XL stick. They are running at the fastest I could get the XL to run, and at .1v lower. 3-3-3-6 2.8 at 205FSB (410MHZ DDR). So that isn't a big deal.

    As far as timings, they are highly adjustable to that also shouldn't be a big deal. Also, I have control over the divider so doesn't that mean I can bump it to whatever level I want, it won't switch to 2700 I believe.

    Anyways, I just didn't want to damage anything. I'm gonna get some sandra numbers before and after and post them up. I just got out of a 24 hour run on Memtest86 with these sticks and all is good for stability at this level.

    As for overall performance, I will have an extra 512mb of memory but bandwidth may be lower, is that an improvement?
  • madmatmadmat
    edited March 2006
    RTM: From the manual "Supports 2 DIMMs DDR400, supports 3 DIMMs DDR200/266/333"
  • lemonlimelemonlime Canada Member
    edited March 2006
    madmat wrote:
    RTM: From the manual "Supports 2 DIMMs DDR400, supports 3 DIMMs DDR200/266/333"

    Ahh, I stand corrected. Looks like they impose this to reduce stress on the northbridge. I'm sure there is a good chance it will still run at DDR400 if it is set manually.

    SmiDig: Depending on what you use your PC for, 1.5GB could be much more useful than 1GB at higher bandwidth. If you play BF2, or do any type of CAD etc, the extra ram should be worthwhile. Of course this is assuming that you can not get it to run at DDR400. If you can get it all running at full speed, it's a pretty obvious winner :)
  • muddocktormuddocktor
    edited March 2006
    Yeah Matt, that's why I said to run memtest. The mobo manufacturers like to err on the side of caution a lot of times too, when writing up the manual. I definitely would give 200 MHz ram speeds a try though and see how it does. You can also try bumping the nb volts up a little too, if stability with the ram set synchronous looks a little marginal. Just don't expect to get ram speeds much higher than 200 MHz with 3 dimms in the board.
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