Memory upgrade - dual channel or not

I got a Dell 1720 inspiron and need to upgrade the ram from its current 1 GB.

I called up dell tech support and they told me ram was in dual channel mode and only 2 memory slots are there in the machine. She told me that it is mandatory to have memory in dual channel mode only.

My questions

1) Should i upgrate to 2 GB (using 2 * 1GB sticks) or buy a 2 GB stick and remove one 512 and have 2.5 GB (1 * 2 GB and 1 * 512 Mb)
2) Should i run the laptop with dual channel memory only? What gain can we expect using dual channels ?

I am not looking at this laptop for use as a gaming machine.

Thanks in advance.

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Current Specs:
Intel Core 2 Duo T7500
1GB, DDR2, 667MHz 2 Dimm
128MB NVIDIA GeForce Go 8400
160G 7200RPM SATA hard drive 7200RPM
OS: Vista Home Premium

 

In order to run your RAM at dual channel mode, both RAMs have to be identical. So, having a 1 GB and 526 MB RAMs in pair would not make them run at dual channel mode. I am not so sure about real life performance gain from dual channel.

You can read more about your particular system at Crucial Memory website:
http://www.crucial.com/store/listparts.aspx?model=Inspiron 1720

 

More ram will always be better than dual-channel.

 

I double checked, and the system will work even if the memory is not running in dual channel mode. The benefits of dual channel is that it doubles the bandwidth between the memory and the rest of the system. In single channel mode it can potentially take twice as long to read files from memory. The thing to keep in mind is that the actual benefit of dual channel memory depends on what exactly you are doing with the computer, and the size of the memory reads/writes the applications use. As Allan says, more memory is probably going to be better than dual channel, but it depends on what exactly you use the computer for.

The system supports DDR2 SDRAM with a memory speed of 667 Mhz. Each slot can use a stick of 2Gb or less (max, 4Gb total). Please keep in mind that on a 32-bit system the largest amount of addressable (usable) memory will be somewhere between 3.1 and 3.4 Gb, depending on installed hardware, due to the way the computer uses the higher address ranges.

If you have any other questions on this, I'll be happy to answer them.

Larry
Dell Customer Advocate

 

This is simply not true on current generation chipsets.

Generally speaking, on current (and last) generation chipsets, having both channels populated with different sized ram, will run in asymmetrical dual channel mode. Having both populated with same spec ram will run in symmetrical dual channel mode.

Theoretically, symmetrical dual channel mode is faster than asymmetrical. But in real life the difference is so minute as to be basically non-existent.


For more information, do a google search.

 

In general it'll be it'll be reasonably cheaper to buy 2 x 1GB than 1 x 2GB. Symmetric dual channel will also give a small, small performance boost over asymmetric dual channel. From 2GB to 2.5GB there probably won't be a huge jump in performance.

In other words, I'd go with 2 x 1GB over 1 x 2GB.

 

See the dual channel thread for various test results.

John

 

Where will be much performance enhancement between moving from 1 to 2 Gb (2 x 1Gb) or (1 x 1Gb and 1 x 2Gb) ?

 

Well, I upgraded to 2.5 gigs from 1 gig, and although I haven't run any memmory intensive applications except some games, there has been a difference. Slightly faster boot up/ sleep time, and STALKER does not freeze up when I'm walking around from loading the environment. Half life 2 and other steam games also don't take forever to minimize and then maximize. Vista definitely needs more than 1 gig...

 

According to the documentation, the Inspiron 1720 will only use dual channel mode if it has a matched pair of DIMMs installed. I'm not sure how much difference you will see between 2Gb in dual channel, and 2.5Gb in single channel mode, but either solution will be noticeably better than 1Gb of memory.

Larry
Dell Customer Advocate

 

Dual Channel's benefits are small and unnoticable. You'll see MORE noticable performance gain with an extra 1gb of memory over Dual Channel.

Think about it, when the OS runs out of memory, it goes to the harddrive. ANY memory at all is faster than the HD.