Single-channel memory mode & system performance bottlene

[hydrostarr]

Does a system with with 2 differently-sized memory DIMMs present any significant overall-system performance degradation (and not just memory performance degradation)? I understand that the memory interface may not be as fast (according to this post: http://forum.thinkpads.com/viewtopic.ph ... 473#114473 ), and I'm curious to see how much affect this "single channel memory mode" has on various system-performance scenarios. eg, intense-cpu-to-memory communication may degrade--but how much? Also, how much migh this affect "general" PC usage scenarios (email, browsing, spreadsheet, editing, OS bootup, etc)?

I current T41 (2378DHU) has both a 512 and 256 MB DIMM, and I'm wondering if this degrades my system performance (a different measure then "memory performance") at all. I think I will have applications for my next Thinkpad purpose ( http://forum.thinkpads.com/viewtopic.php?t=18180 ) that may experience a system bottleneck in the "single channel mode."

Thanks for any help,
-Matt

[dr_st]

First of all, the performance increase of dual channel RAM is 5% tops, and we're talking just about the RAM subsystem. Your CPU, HD, etc. is going to be just in fast, whether in dual channel or single channel. You will never feel a [censored] thing.

Second, dual channel on the latest notebooks can work between DIMMs of various sizes as well.

Third, your T41 doesn't suppor dual channel memory mode, no matter what DIMMs you put in there.

Finally, I haven't heard of any particular problems arising when using RAM modules of different sizes, whether related to dual channel or general use. You should be fine.

[hydrostarr]

Ok, good info.

How might these things apply to a T43? Will there be any significant performance different between 2, 1GB DIMMs and 1, 2GB DIMM?

And would there be any significant degradation in a (edit) 2.5 or 3 GB config for a T43?

If the above info applies to a T43 as well, then none of it is an issue, but I thought I would check before I plunk down more then a couple grand on this machine.

-Matt

[dr_st]

How might these things apply to a T43? Will there be any significant performance different between 2, 1GB DIMMs and 1, 2GB DIMM?

I already answered that question, no?

And would there be any significant degradation in a (edit) 2.5 or 3 GB config for a T43?

First find a way to stick over 2GB in that machine, then we'll talk.

[hydrostarr]

How might these things apply to a T43? Will there be any significant performance different between 2, 1GB DIMMs and 1, 2GB DIMM?

I already answered that question, no?

In the context of a T41 yes. In the context of a T43, no. Maybe you meant "all models," with your answer, but I'm just be clear and thorough, just to make sure. Can you clarify? Thanks very much for your time.

-Matt

[dr_st]

First of all, the performance increase of dual channel RAM is 5% tops, and we're talking just about the RAM subsystem. Your CPU, HD, etc. is going to be just in fast, whether in dual channel or single channel. You will never feel a [censored] thing.

That's a general statement about the technology in its current state. No matter what CPU/motherboard/RAM you use.

The T41 remark was merely to show that this question is irrelevant for that laptop, because it doesn't support dual chan to begin with. Neither does T42 for that matter.