Running 2x256, 1x512 in Dual Channel on Abit NF7-S

[simms]

Is this possible? I have 2x256 PC3200 of CH-5 at stock. I want to buy another stick of 1x 512 PC3200 and get it in dual channel.

I would do it like this:

Slot 1: 1x512 PC3200


Slot 2: 1x256 PC3200
Slot 3: 1x256 PC3200

On the NF7-S, two memory slots are together and one is further away. If I buy a stick of 512, can I get this to run in Dual Channel at DDR400?

Thanks.

 

[mechBgon]

Small picture: there is no way you can use three modules on that board and not end up with dual-channel operation

Big picture: dual-channel operation doesn't generally do much on nF2 Ultra400 anyway, the glass is already 96% full

 

[simms]

Really? I'm sure if I put in a 128, 256 and 512 stick in random slots, it wouldn't run in DC now would it?

 

[mechBgon]

It would! nForce2 dual-channel chipsets work in a counter-intuitive way. Also, I remember pspada doing some UT2003 Demo Botmatch benchmarks to see if it mattered whether the amount of RAM between the two channels mattered or not, and he found that the results were basically identical. So I wouldn't worry

I used to use three 512's on my nF2 boards and that worked fine (well ok, the 8RDA+ did just die one day, but other than that...).

 

[simms]

Right, but that's 3 of the same stick. If I bought 2x256 CH-5 chips, and got a 1x512 ValueRAM with other timings, you're telling me this would run in DC?

Your answer may very well tell me what my next purchase will be.

 

[FlyingPenguin]

You need matched pairs for dual channel. It would probably run with the 3 sticks but either onely the matched pair would running in dual channel or (more likely) it wouldn't run in dual channel at all.

 

[Sforsyth]

I have a nF2 Ultra400 MOBO and I had 2 mismatched brands of Ram 2x 256 PC3200 and I'd get strange memory errors once and a while so I got 2X 256 MB PC3200 of Matching Brands and it fixed the problem.

 

[dguy6789]

Let me explain it. Dual channel mainboards for Athlon XPs have 3 slots for memory. 2 of the slots are one channel, and the other slot is the other channel. If you have 512MB in channel 1, and 512MB in channel 2, you will get 1GB of dual channel. If you have 512MB in first slot, and 512MB in second slot, and 512MB in the last slot, you have 1GB in one channel, and 512MB in the other channel. You can only run dual channel speeds with the lowest amout of ram in each slot. Since each channel has at least 512MB, it would run 1GB of your memory at dual channel, and if a program got to the last 512MB stick, it would revert to single channel.

If you put 256MB in a slot on channel one, and another 256MB in a slot on channel one, and then a 512MB in channel 2, you would get perfect dual channel because both channels have 512MB of memory. If you put 512MB in channel 1, 256MB in channel 1, and 256MB in channel 2, you would get 512MB of dual channel, and the last 512MB would not be.

Bottom line: It doesnt matter how many dimms you have or their sizes. Just make sure the AMOUNT of ram in each channel is equal.

Note: Not all Athlon XP boards have the slots in a channel 1, channel 1, channel 2 order. Make sure you know for sure which dimm slots are for what channel.

 

[mechBgon]

The amount of RAM in the various slots does not need to be balanced on nF2 Ultra400. You can do it, it will make your brain look like this --> but it won't make a difference. Anand's articles on the original nForce dual-DDR chipsets might help with the concept of the crossbar that lets both memory controllers reach all three slots all the time.

 

[dguy6789]

They dont have to be balanced, but if they are unbalanced, you are not running true dual channel. Kind of like half and half.

 

[simms]

Thanks guys.

If you put 256MB in a slot on channel one, and another 256MB in a slot on channel one, and then a 512MB in channel 2, you would get perfect dual channel because both channels have 512MB of memory.

Meaning I would get 1GB in dual channel then, correct?

And one more thing: What about TIMINGS? CL2 and 2.5? CAS latencies? Should I be worried about this as well?

 

[dguy6789]

If you have 512MB of memory in channel 1, and 512MB of memory in channel 2, you would have 1GB of dual channel memory. Don't worry about timings too much. The lower the better, but the difference is not noticable anyways. If your not prepared to do a bunch of stability testing and lots of computer restarts, just leave timings alone.