mem not working in dual channel

[cg84]

i've got an intel d865gbf mobo and a p4 2.66ghz alongwith a gigabyte radeon 9600se 128 MB card. till recently i had RAM of 256MB DDR266. now i've added another 256MB DDR266 stick. the problem is that this config isnt working in dual channel mode even though the sticks are installed in channel A DIMM 0 and channel B DIMM 0, ie they are matched symmetrically.
now, i've done some googling and what i know is that for dual channel config the sticks shd have...
1. Same density
2. Same DRAM technology(128 M-bit, 256M-bit, 512M-bit)
3. Same DRAM bus width(x8 or x16)
4. Both either single or double sided

the densities are same, of course. but how do i find out the DRAM tech, DRAM bus width and whether the sticks are single or double sided??couldnt find much with google...plz help.

also note that that on both the sticks 32Mx64 is printed, and one of them has half the ICs as compared to the other.

thanx,
chaitanya

[icecoolz]

One quick question. How do you know that it isnt working in Dual channel mode ? You havent mentioned it.

[geek_rohit]

The BIOS displays whether the memory in working in Dual Channel or not. Also the Messages coming during the booting sequence displays the mode in which the memory is running. Try getting some memory modules from your system vendor or from friends just for checking and check. There must be some difference in the modules. Otherwise the RAM should work in Dual Channel.

[cg84]

yes, the bios and the post screen both display the memory mode.
rohit, of course there is a difference in the modules. thats why its now workin in dual channel mode. and i will get them replaced alright, but what i want to know is how do i find out the DRAM technology and the bus width of my modules, and wether they are single or double sided? any ideas??

[cg84]

plz note - single or double sided is not as simple as wether the chips are on one side or both sides of the board. even if all the chips are on the same side, half of them maybe electrically connected from the other side. so its better to refer them as single or dual bank DIMMs. i've looked at the modules carefully, and i believe that both are single bank, but i still don't know the DRAM tech and the bus width...

[cg84]

and the opposite can also be true...ie even if the chips are on different side...they might actually be hardwired(electrically connected) on the same side. and i think i can now find out wether they are really single or dual bank...

"Tip: Here is a trick to check if your DIMM is single-sided or double-sided -- if there are traces connected to golden finger pin 144 and pin 129 of the DIMM, the DIMM is probably double-sided; otherwise it is single-sided."

found this on another forum. will hv a look at this thing.