dual channel vs more memory

I currently have 512 mb on my laptop and wanting to put another 512 mb...if I wanted dual channel I probably would have to get the ram from manufacter that would cost around $70+...it's almost same as buying 1 gb ram if buying online. so which is better, 1gb dual channel or 1.5gb without dual channel?

 

1.5GB. The extra bandwidth provided by dual channel is rarely used up. But Windows will be able to make use of the extra memory any day. Also for dual channel you can use any 512MB stick which has the same specifications as the current RAM. It does not need to be from the same manufacturer.

 

in cpu-z it shows my memory timing 4-4-4-12
I found this one at 4-4-4-11...would it work?
http://www.newegg.com/Product/Product.asp?Item=N82E16820145554

kinda hard to find right timing most usually says timing at 4 and nothing else...

 

It should. If you add a faster memory to a slower one it should run at the same speed as the slower memory. If you add that one it should make it run at 4-4-4-12.

 

ah ok i got it, thanks

 

Just wanted to point out that, if you run 2 banks of memory that are not identical you will no longer get dual channel. indentical means size and all timings. so both 512MB, but slightly different timings will work, but will not be dual channel. miner is right, that memory op freq will clock to the slower chip, but the latencies will not adjust.

At least that is my understanding.

[Correction] - Only size/capacity has to be identical to get dual channel. memory chip technology can be different. So the latencies will not adjust, but the system will operate in dual channel mode, where addresses ping-pong between the two channels. On further thought this makes sense since no two chips, matched or not, are going to perfectly identical in timings, etc.

 

really cant get what you mean...
lets assume i bought the 4-4-4-11 and i have 4-4-4-12
so the one with the 11 wont change to 12
but it will still run dual mode?

I still haven't made my mind which to buy hehe..because I always prefer buying online because its cheap...512mb 533mhz in store cost prob almost as much as a 1gb 533mhz online...

but if buying a 512 mb 533 online will be cheaper...but will run a risk of not running dual channel and really don't like to online return/refund...

 

I'd just get more memory - dual channel does almost nothing in terms of performance.

AnandTech did a test to see if it made any difference in speed in OS X and Windows, and it didn't make any. Click here for the review.

 

I'll start with the advice first and the explanation second.

Advice: If you go with 1GB min, then get 2 512MB chips. In your case I'd just buy another 533Mhz 512MB chip, it's the cheapest route and you'll never notice the difference with 667. For most normal uses, you probably wouldn't notice the difference between 1GB and 1.5GB. (See Tom's Hardware, they have a nice article on "how much memory you really need") This article shows a negligible performance gain for memory increases in the 1-2GB range. 512MB to 1GB is a big gain. That being said, a stick of 1GB 533Mhz is only going to cost you $80 or so. If you keep your original 512MB, don't bother getting a 667chip, stick with 533.

******The explanation on Dual Channel modes*********

Been thru this pretty extensively today in another thread, so here's the short version.

Dual Channel simply requires both slots be occupied, size, time, freq do not have to match.

However, the Dual Channel benefit that everyone implies you will get only occurs when the size of the memory in each channel is identical. I know this is true for the Intel 945GM/PM chipset. In Symmetric mode (equal size in both channels) addresses ping-pong between channels, so you effectively get overlapping (simultaneous) access on each channel; that is, the system will initiate a read on the other channel before the first one is done, which is why timings don't have to match, just size.

If you have two different size chips in the 2 channels, addresses are dealt with one chip at a time until it maxes out, then it goes to the next chip. For example, if your memory was full and you were reading it out, you would read out the first chip, then read out the second. In Symmetric dual channel, you'd read them out in an overlapping manner, virtually simultaneously.

I'm sure I muddied the waters even more. buy a 1GB stick of 533 and go for 1.5GB. good luck.

 

Here's another question to keep things confusing:

I just ordered a Toshiba Satellite M100 with the minimum memory (1x256MB, 533). I plan on buying a single 1GB stick of memory (newegg has 1x1GB/667 for $90). Now, should I simply add the 1 GB in addition to the 256 to use 1.25GB total (@ 533)? Or, should I remove the 256 when I upgrade, so as to keep the memory running at the higher 667?

Thanks!

 

If you are going to keep the 256MB 533MHz, then no need get 667Mhz 1GB. It will clock down to 533, so there is no speed advantage. 533 1GB stick will only be a few dollars cheaper.

 

To rephrase the question:

Is 1.25 GB @ 533 preferable over 1.0 GB @ 667?

 

Does your M100 have integrated graphics? In that case gettin the 1.25GB is a better idea as the graphics card is allocated 128mb & if you get 1GB then it will be reduced to somewhere around 800mb, but with 1.25gb you still get over 1GB RAM. Performance wise you wont notice a difference but psychologically it makes a difference as you would know that the system still has 1GB+ left for use by Windows.

 

nbr42206:
hehe i guess ill just get the 1gb like you said
thanks for the help

mathias:
i dont think 533 and 667 isn't going to be much faster but id get 1.25 at 533 than 1.0 at 667mhz...

 

Dual Channel does help memory bandwidth, but it's nothing major, so more ram is more beneficial than running the same amount of ram in dual channel.

Ram is cheap these days so go with more ram, and if you can get two sticks of 1gb and run them in dual channel.

 

For the original poster, how is your ram allocated now? Most laptops that come with 512 mb will have 2 256 mb sticks as this is usually cheaper for the manufacturer. This is even moreso the case if your notebook supports dual channel. 512 dual channel is 2 sitcks of 256. In this case, If you want 1 or 1.5 gb, you will need to buy at least a 1 gb stick. Only buying a 512 will leave you with 768 and an extra 256 laying around. If you want 1.5 gb, you need to buy a 1 gb and a 512. Best bet is to just buy a 1 gb stick so tha way you end up with at least 1 gb for windows even with your intergrated grpahics like others have said.

 

mines 1 sodimm 512mb...but then ill just wait a bit since I have been spending alot of money and also i just bought the laptop so really dont wanna spend much right now hehe

prob wait a bit and later buy 1gb instead

 

Whereas, I ordered Inspiron e1705 with CoreDuo 2.0mhz @ 677 (FSB?) and 1gb of 533mhz RAM.

Will it not degrade PC's performance for CPU to run faster than RAM?

What's the difference between 533mhz and 677mhz RAM?

And, will I benefit much to upgrading from my current 1gb, 533mhz to 2gb 677mhz?

 

you won't notice any slower performance in a 533mhz, its just that the core duo laptop can handle the maximum 677mhz rams, so you can still put a ddr2 400 mhz if you want to.

you won't benefit much in upgrading the mhz...

I don't exactly know why it seems the mhz seems so important but it is hard for me to tell the difference of a ddr 333mhz and ddr2 533mhz in performnce between 2 laptops...hehe....but you can really tell when youre low on memory difference..

You're pretty much set right now....

 

Get rid your old memory so it can run at 667Mhz

 

In my limited knowledge and experimentation on DT, higher DDR speed also means Higher CL. One of the BM utilities (SPD in cpu-z?) shows this nicely.
If your BIOS allows tweaking DRAM settings [VDC, CL, DDR] then you can get some advantage, but I think XP/Hardware maxes out around 6.4 Gb/s bandwidth no matter how much Mem is in system. [XP limits ~3GB]
I think new 667 should run @ 533 OK with a faster CL=4.
Then later when you can afford/buy 2nd 667 you will run 667 @ CL=5
I have no idea what Core Duo is capable of. Test it out w/ BM utilities & let us know! D8D

 

Yep. Still waiting on that laptop I ordered...soon as it's mine, I'll put it through its paces.