T43 dual channel DDR support ?!?!

[danT43]

This is driving me crazy. I have just upgraded my memory with a second 512MB chip from IBM (same part # as the one in slot 1). T43 is supposed to support dual-channel DDR if I am not mistaken (Intel915 chipset sure does).
Now kill me if I know why, bandwidth test with two and with one memory module shows the same result.

So my question is this:
Does T43 really support Dual channel DDR or it doesn't?

ThinkPad T43 266898U

[RonS]

I've never heard of the T43 supporting a dual-channel memory interface. If it did, I can't imaging it would be much more than a 10% difference in performance.

On this page the memory is spec'd as PC2-4200, but no mention of dual-channel.[/url]

[K. Eng]

The 915 series chipset does support dual channel, but there is little or no performance benefit unless your system has integrated graphics. The Pentium M's Front Side Bus can't take advantage of all the bandwidth.

I suspect that the T43's with discrete graphics (like Radeon X300) have only 1 memory channel enabled.

[dfumento]

You can read more about DDR2 memory performance and the Intel notebook chipset in the Tomshardware link in the FAQ in my signature.

[RonS]

But remember that DDR2 has nothing to do with a dual channel memory interface.

There is no such thing as "dual-channel memory." Dual-channel refers to how the memory is used, not what kind it is.

[danT43]

You are absolutely right.

My question was DOES T43 SUPPORT DUAL-CHANNEL MODE when two identical DDR modules are installed.

[RonS]

I think I can safely say "No."

[danT43]

that is too bad

[franzose]

I think I can safely say "No."

This is not correct!

I added a Kingston memory module on my T43 (26684NG) and with both modules it enables dual channel mode!

See the screenies:

http://www.vaslet.org/IMGP2848.JPG

http://www.vaslet.org/dual.JPG

Edited by Moderator: That was a nasty shock for anyone on dialup. Don't put pictures in messages without a warning in the subject line. Use links instead.

[v_parthi]

Hi,

T43/T43p does support dual channel according to tabook (Bill's sales page).

For the new Pentium-M, the FSB is 533 Mhz. So, for example you can add 1 512MB PC2-4200 DDR2 533 Mhz RAM or 2 X 256MB DDR 266 Mhz RAM in dual channel. Both have advantages & disadvantages.

DDR2 is a fast single chip, less power consuming, etc.. The DDR in dual channel mode is slightly better sometimes for the above example.

But your case is totally different. You got DDR2 memory & when you enable dual channel, you underclock it to 266 Mhz to match the CPU, which should theoretically degrade the performance especially when you run small applications. Meanwhile, when you run both 512MB modules in 533Mhz frequency in dual channel, you overclock the Pentium-M. I don't know if it's possible.

Please correct me, if I am wrong.

regards
Parthiban.

[franzose]

For the new Pentium-M, the FSB is 533 Mhz. So, for example you can add 1 512MB PC2-4200 DDR2 533 Mhz RAM or 2 X 256MB DDR 266 Mhz RAM in dual channel. Both have advantages & disadvantages.

DDR2 is a fast single chip, less power consuming, etc.. The DDR in dual channel mode is slightly better sometimes for the above example.

But your case is totally different. You got DDR2 memory & when you enable dual channel, you underclock it to 266 Mhz to match the CPU, which should theoretically degrade the performance especially when you run small applications. Meanwhile, when you run both 512MB modules in 533Mhz frequency in dual channel, you overclock the Pentium-M. I don't know if it's possible.

Please correct me, if I am wrong.

I think you didn't get the meaning of dual-channel right. It has nothing to do with frequency but with interleaving the RAM sockets to get more throughoutput.

In my example, DRAM is running at 200MHz with 2:3 divider. This means a FSB of 133 MHz for the CPU (FSB 533 quadpumped in Intel specs).

[aamsel]

Well, if this is true (that dual-channel is supported), then you would not want to add a 1GB DDR2 module as an upgrade to the 512MB DDR2 module that comes with most T43's ????

Andrew
Austin, TX