help upgrading laptop memory(dual channel mode)

[javier_machuk]

I have an hp dm4 with an i5 430m(arrandale) and 2x2GB ram pc3 10600s 1.5V, lately i have been reaching really close to top that ram and i want to upgrade but expending the least ammount possible.
If i replace only one sodimm with a 4GB one, would that make me loose the dual channel operation? would it be noticeable if that happen? because i think 6 GB total would be enought for me and that would only cost me 25$, but if it is true that i would loose the dual channel mode and have a noticeable performance hit i might go to a 2x4GB kit for around 55$.
PD. did anyone tried 8GB dimm with arrandale? because intel says max total ram is 8GB in 2 channels, i guess meaning 2x4GB.

 

[LTC8K6]

If you lose DC mode, you will not notice it. The difference in performance is very small.

More ram is almost always better than ram that's a little faster.

6gb of single channel ram is better than 4gb of dual channel ram. :biggrin:

 

[Blastman]

If you lose DC mode, you will not notice it. The difference in performance is very small.

This.^

The difference between single channel and dual channel memory performance in the vast majority of applications is nothing to very small except for a few memory intensive benchmarks or applications.

THG i7-Nehalem …

We ran the entire benchmark suite once with each of the memory configurations. Our conclusion? It doesn’t matter much to the Core i7, with its 1 MB L2 cache and 8 MB L3 cache, whether it is running its memory in a triple-, dual-, or single-channel configuration. In everyday tasks, there is absolutely no tangible performance difference: the performance delta between a tri-channel and a single-channel configuration is only 2% on average.

Since your laptop only has 2 memory slots, if you run 2 different size memory sticks … say 4GB + 2GB, your motherboard will actually run in what's called flex-mode -- a combination of dual channel/single channel.

Intel flex mode

Flex mode

This mode results in both dual and single-channel operation across the whole of DRAM memory. The figure shows a flex mode configuration using two DIMMs. The operation is as follows:

•The 2 GB DIMM in slot 1 and the lower 2 GB of the DIMM in slot 2 operate together in dual-channel mode.
•The remaining (upper) 2 GB of the DIMM in slot 2 operates in single-channel mode.

This flex mode should be as fast as dual channel mode the vast majority of the time.

 

[javier_machuk]

thanks to both of you! I suspected that there was something like that intel flex mode, but now i can confirm it, i think i'll go with only one 4GB dimm.. i'll let you know how it goes.

 

[i7Baby]

From http://www.cnet.com/au/products/hp-pavilion-dm4/specs/

Looks like you should be able to keep one 2gb stick and add a 4gb stick giving you 6gb in total.