dual channel ram with different size sticks

[rommie]

I have an older (2k4) socket 478 mobo here, which currently has 4xddr1-400 512mb sticks in it. The bios says dual-channel is enabled. I've gotten my hands on 2x1gb ddr400 sticks. Just wondering, can I take out 2 of the 4 512 sticks, replace with the 1gb ones, and still have dual channel enabled?

 

[EarthDog]

That shouldnt be a problem, so long as the timings and voltages of the new sticks match the other. Otherwise it will default to the loosest timings and such. But Dual channel should still be there I would imagine...

 

[bgd73]

I have an older (2k4) socket 478 mobo here, which currently has 4xddr1-400 512mb sticks in it. The bios says dual-channel is enabled. I've gotten my hands on 2x1gb ddr400 sticks. Just wondering, can I take out 2 of the 4 512 sticks, replace with the 1gb ones, and still have dual channel enabled?

yes that works. I am running that same scenario as we type. socket 478, 2xs1gb, and 2 512mb, ht enabled, dual channeled. alternate according to the book. I am also on 865 chipset, thatmay have a difference.
I knew to stop at 3gb (32bit) and system match the vid card (either 800 or 400mhz memory) around 512-1gb, it is a nonchalant math goodness. AGP still does something not much talked of, in memory matching.

if you run into something odd, check vid card specs. agp aperture also gets maginfied huge. 64mb agp aperture in bios is 315 to vista premium, assume HT throwing it off, just like the beginning of thse setups some years ago now.

 

[redduc900]

For a dual channel (interleaved) mode configuration w/ four DIMMs, it needs to be set up like the picture below...

To achieve Dual Channel mode, the following conditions must be met: 

Matched DIMM configuration in each channel 
Same Density (128MB, 256MB, 512MB, etc.) 
Matched in both Channel A and Channel B memory channels 
Populate symmetrical memory slots (Slot 0 or Slot 1)