IC7-G & 2 DDR sticks in DIMM 1/3 => dual OR single channel

[enthu256]

Hi Guys, Just recently discovered this forum... used to follow many of your posts at AT. I finally got the guts to build a o/c rig, but have a curious situation:

Have 2 infineon 256MB 2700 DDR memory sticks populating DIMM 1 & 3 in a P4 2.6C GHz IC7-G system.

CPUz v1.19 reports that the memory modules are in a "Single Channel" mode, instead of "Dual" channel! Shouldnt' it be in "Dual Channel" mode??

Have tried the following to get "dual-channel" performance:

1) tried the various CPU:Memory ratios 1:1, 5:4, & 3:2.
2) tried the system at default FSB & tried it overclocked as well. (FSB=250 & CPU:MEM=5:4)
3) mostly kept the BIOS memory SPD/Perfomance options at default.
4) Have also swapped in 2x 512MB 2700 DDR Infineon/Samsung
sticks (which are double-sided) in DIMM 1/3.
5) Also tried DIMM slots 2 & 4 as well.

In all these situations, I am stuck with only the "Single" channel mode. Whats up with this? Am I missing some obvious setup in the BIOS?!

Interestingly, memtest86 reports a bandwidth of ~1500MB/s which correlates well with SiSandra's UnBuffered Memory BW test.
(I believe this is ~bandwidth I would expect for a single channel mode).

Sure could use some help in figuring this mystery.

Thanks in advance for any suggestions you folks may have!

[ThugsRook]

my testing has shown that performance and stability of 1+3 and 2+4 to be indenticle and both are dual channel.

im not sure what could be the problem but ill try and think of something for ya :wave:

[enthu256]

thanks for responding thugs...

a few other things I tried - different IC7-G motherboard, and I
still had the same issue. I "reused" the WinXP
install, but I suppose that may not be a problem,
as I get the low memory bw even in memtest86.

also tried with a 2.4b & 2.4c processors.

other perhaps irrelevant info: have an ANTEC 430W supply
harddrive is a 120gb on sata1 using serillel2
ide1 had another 120gb hd
ide2 has a dvd
the videocard is a old AIW 128 PCI
dont have any other PCI cards installed.

(these were the common items, when I swapped the
MB, and the CPUs)

are there any jumpers on the MB that needs to be set?

hmmm... there must be something systematically wrong!

[ThugsRook]

looks like youre down to blaming the ram huh?

have you tried bios v14?

it is detecting all 512mb right?

[enthu256]

well .... I am really puzzled.

I have tried a different pair of memory as well 2x 512MB 2700 DDR ( 1 stick is Samsung, the other is Infineon) And I am able to o/c all these memory stick to even FSB 200, CPU:MEM=1:1

have even tried all sticks - 1.5GB of memory - all 4 banks populated at stock, and 5:4.

in each of these memory combinations, the total memory reported by the MB is correct.

so, the one thing that I have not swapped around is the AIW PCI card... I dont have another card to try, but somehow, I find it hard to imagine the PCI video card causing this mystery.

I have use bios 1.3 (but I didnt pay attention to the memory speed at that point). I have tried bios 1.5 and 1.6...

gotta try bios 1.4 it would be cool, if that resolves this!

more soon.

[enthu256]

nope. bios 1.4 also stubbornly gives me only "single-channel"
hmmmm... any other ideas, thugs?
maybe, for good measure, I should swap out the AIW PCI card
and try 2 more sticks of memory...?
let me know. thanks for your help so far!

[ThugsRook]

ummmm, try 1 stick and see if it shows as dual channel? :scratch:

try new ram.

[Jim]

Too weird....basic idea.
Remove bios battery, clear bios with J1...load defaults. :confused:

[ThugsRook]

might wanna unplug/turn off the PSU 1st ;)

[enthu256]

Yup, I didnt mention this before. but I tried 1 stick just to see what bandwidth memtest reports, and it matched what I had with 2 sticks (or 4!). Although at that point, I didnt pay attention to cpuz for that test. but I can check that as well.
(I also tried DIMM 1+2 just for kicks - same result!)

Whenever I updated my bios, I would switch OFF the PS (Antec 430) in the back. And reset the CMOS with the jumper. And
I have gone between 1.4 1.5, 1.6 too many times this week.
I know(?) the reset is effective, because I have to setup my BIOS
IDE/SATA options, etc.

I will try the reset again after pulling the plug/battery out, but at the moment my hair is all that is getting pulled out :(

tonite, I plan on replacing the last two items that I have kept
the same all through - the AIW PCI 128 card, and get 2 more
RAM sticks (other than the 4 I have already tried).

any other suggestions, guys? thanks for all the help so far. somehow, just didnt expect to run into this kind of issue on my first build!

[ThugsRook]

besides blaming a piece of hardware ~ im stumped!
it sounds like you are doing very good diagnostics, but unfortunately getting nowhere :(

ill be keeping an eye on this thread just to find out what the problem is/was myself.

:scratch:

[enthu256]

thugs... u r right. back to basics. the best debugging can
be thwarted by a "poor" assumption.

in my case, it was that 2 memory sticks -
1) same manufacturer - PNY
2) same model - 256MB DDR 2700
3) same label
4) same chip - infineon (different batch? code...)
5) same memory identifier string reported in CPUz
6) AFAIK, same pcb component positions ...

are not identical, as far as the memory controller is
concerned.

This problem should have been ruled out by the other pair
of memory stick that I tried (but that had a slightly different
PCB, so I was really counting on this pair of memory sticks
to be the golden one) Well, it finally took a Kingston HyperX
pair to show me the error of my ways!

Thanks Thugs... and others for all the help.

I am posting this follow up just to caution people, in the case
of memory sticks - identical looking need not necessarily be
identical.