Memory Question.

[klyjr]

My MB supports the dual channel but only on one set of slots .. right now i have 512 (2 x 256's) in the slots. If I but 1 gig of the dual put it in that slot and put the other 2 256's in also is that gonna slow the dual channel in the main slots ?

Gigabyte 8knxp
p4-2.6 ht

 

[skipholiday]

shouldnt effect it.

 

[cdogg]

I disagree. In order for dual-channel to work correctly and in a stable environment, RAM modules should be identical in size and type. Also, likely you have 3 or 4 slots. They are usually color-coded to show you channel A and B. For dual-channel to work, you must have one DIMM on A and the other on B.

On my MSI KT880 board, for example which has 3 slots, dual-channel only kicks in if the DIMM 1 and DIMM 3 slots are filled. If I was to place RAM in the DIMM 2 slot, it would automatically disable dual-channel.


~cdogg
[tab]"All paid jobs absorb and degrade the mind";
[tab][tab]- Aristotle
[tab][navy]For general rules and guidelines to get better answers, click here:[/navy] faq219-2884

 

[jurgen36]

:cdogg
However this seems to be not always the case. my Gigabyte bord manual table states that dual channel will work with slot 0ne and three or slot 2 and 4. But it also states that dual channel also will work with identical memory in slot 1,2 and 3. Well I tried it out, it appears to be correct. But if i put the third chip into slot 4 and not 2 then dual channel is disabled. I can not quite figure this out. It does not work on Asus bords. But populating channel 1 and 3 with 1Gb and 2 and 4 with 512 Mb modules appear to work in dual channel mode on all bords I tested.
Regards

Jurgen

 

[cdogg]

Jurgen:
You always have to pull exceptions out of your hat, don't you!


I would be interested in knowing the Gigabyte model you have. I haven't seen where dual-channel can work (reliably) using an odd number of DIMMs of different size.


klyjr:
OK, I neglected the fact that you posted your motherboard's make/model. I took a quick look at its online manual in light of Jurgen's post. Here's what it says:

1. One, three, or five DDR memory modules are installed: The Dual Channel Technology
will not operate when one, three, or five DDR memory modules are installed and they
will only work as Single Channel.

2. Two DDR memory modules are installed (the same memory size and type): The Dual
Channel Technology will operate when two DDR memory modules are inserted individually
into Channel A and Channel B (DIMM 1 pairs up with DIMM 4, DIMM 2, 5 and
DIMM 3, 6). However, if the two DDR memory modules are inserted into the same
Channel (DIMM 1,2,3 or DIMM 4,5,6) then Dual Channel Technology will not operate.

3. Three or five DDR memory modules are installed: Please note that The Dual Channel
Technology will not operate when three or five DDR memory modules are installed; part
of them will not be detected.

4. If four DDR memory modules are installed (two pairs of DDR memory modules with the
same memory size and type): The Dual Channel Technology will operate when a pair
of DDR memory modules are inserted into DIMM1, 4 and another pair into DIMM 2,5.

5. If six DDR memory modules are installed: To activate the Dual Channel Technology and
to make the size of each DDR memory module detected, please use six DDR memory
modules with identical size and type and insert them into the six DIMMs following the
sequence below:
DIMM 1: Double or Single Side
DIMM 2: Single Side
DIMM 3: Single Side
DIMM 4: Double or Single Side (if DIMM1 is inserted a double-side module, then DIIMM4
must also be inserted a double-side one.)
DIMM 5: Single Side
DIMM 6: Single Side

That should clear up any confusion.

Take note that DIMM slots 1, 2, & 3 are channel A and 4, 5, & 6 are channel B. Also note how slot 1 pairs up with slot 4, slot 2 with 5, etc...


~cdogg
[tab]"All paid jobs absorb and degrade the mind";
[tab][tab]- Aristotle
[tab][navy]For general rules and guidelines to get better answers, click here:[/navy] faq219-2884

 

[jurgen36]

:cdogg
Sorry about not giving the type. The bord in question is the SINXP1394 Limited edition bord. I use it in my wifes computer and as I had 3 256MB 133 DDR modules lying around I fitted them. It works very well in Dual Channel mode. It is also said on the memory installation page. Sorry about giving an exception to the normal rule. As I said before it does not work that way on Asus Shuttle or intel bords. By the way I am now retired but still live in Thailand and have full access to the computer lab.
Regards


Jurgen

 

[cdogg]

Jurgen,

OK, I checked the online manual and here's what I found in your case:

If you want to operate the Dual Channel Technology, please note the following explanations due
to the limitation of SiS® chipset specifications.

1. Only one DDR memory module is installed: The Dual Channel Technology can't operate
when only one DDR memory module is installed.

2. Two DDR memory modules are installed (the same memory size and type): The Dual
Channel Technology will operate when two memory modules are inserted individually into
Channel A and B. If you install two memory modules in the same channel, the Dual Channel
Technology will not operate. Additionally, you can boot the system only when one of the
memory modules is inserted into Channel A or Channel B. On the other hand, the memory
module must be inserted into any sockets.

3. Three DDR memory modules are installed: If you install three memory modules at the same
time, the Dual Channel Technology will operate only when those modules have the same
memory size and type.

4. Four DDR memory modules are installed: If you install four memory modules at the same
time, the Dual Channel Technology will operate only when those modules have the same
memory size and type.

We'll strongly recommend our user to slot into two DDR memory modules into the DIMMs with the same
color in order for Dual Channel Technology to work.

As you can see, it is possible for you to have 3 DDR DIMMs in dual-channel. However, it is noted here that they must be of identical size and type. Also, the recommendation is to go with a 2-DIMM configuration.

This SiS chipset is an exception to many rules! Only motherboards with this particular one can get away with it that I've seen...




~cdogg
[tab]"All paid jobs absorb and degrade the mind";
[tab][tab]- Aristotle
[tab][navy]For general rules and guidelines to get better answers, click here:[/navy] faq219-2884