Memory questions...

I hear all Santa Rosa processors use the mobile 965 chipset so it should support up to 4GB of RAM, but I have a questions:

1. Is it possible to have one 2GB stick and 2x1GB sticks in three slots to make 4GB in such a machine? I think I once heard that memory works faster or more efficiently when connected up in pairs, but I don't know how accurate that is.

2. Do Santa Rosa notebooks support 2GB memory sticks in the first place? Intel's pdf on the 965 motherboards states that it has support for 256, 512 and 1024MB sticks but doesn't mention 2GB.

3. Are generic or 3rd party 200-pin SODIMMS compatible with most notebooks? I would assume so but I ask because I've seen some ridiculous prices for memory upgrades when 2x1GB sticks go for around £45 - £60 and I was wondering what could possess a company to charge hundreds of pounds for things like this.

 

Notebooks only have two slots for memory, so to achive 4 GB of RAM, you would have to have two modules of 2 GB density each. Santa Rosa probably does support 4 GB or more of total RAM, but it comes down to the motherboard if it supports 2 GB modules. Its likely, though, in newer models that they will support 2 GB modules, because of the increase in RAM requirements of many applications.

Practically all third party RAM modules will work in most notebooks. Brands such as Crucial, Corsair, OCZ, G. SKill and others, have a reputable name, and should work in most notebooks. Some people have had problems with double sided and single sided RAM, but thats a limitation of the motherboard, and not a fualt of the RAM modules itself.

 

This isn't possible as unlike desktops notebooks only have 2 memory slots and not 3 as you were wondering. If you want 4GB today in any notebook you will have to get 2x2GB sticks. Connecting up memory in pairs is called dual channel and it doesn't really make much of a difference to memory performance but today there is no way for you to run 4Gb of memory in a notebook and it not be in dual channel (2x2Gb=dual channel).

 

somewhat misleading above:

"it doesn't really make much of a difference to memory performance but today there is no way for you to run 4Gb of memory in a notebook and it not be in dual channel (2x2Gb=dual channel)"

dual channel memory CAN make a performance impact in memory/processor intensive situations. if you have a front side bus with more bandwidth than the memory has (think santa rosa: fsb=800mhz, memory=667mhz) than without dual channel memory, your processor will be waiting around some of the time.

expect 15-20% performance increase in specific memory/processing intensive apps as described above.

also- dual channel memory requires not only 2x2 gig sticks- but, often, they have to be the SAME model memory (sometimes, not always). that means that you could buy two different branded memory modules, each 2 gigs, put them in the notebook, and it wont necessarily run in dual channel mode. if you buy two modules with different speeds, both will downclock to the lowest speed in dual channel mode, if it runs at all.

so, depending on the notebook, you CAN have 4 gigs of ram without dual channel memory. and dual channel memory is a good thing to have because it increases performance without adding cost.

also- the reason santa rosa doesnt specify 2 gig modules is because santa rosa is a platform, its a standard. you have to meet certain specs to say you have "santa rosa" and 2 gig memory module support is not one of those specifications. however, motherboard makers are free to add features to their products as they choose, on top of santa rosa, and many now support 4 gigs of ram.

hope that helps.

 

How certain are you that laptops only have 2 memory slots? This link states that the Zieo has two occupied slots and one free, meaning it has three in total. Assuming this is true then, having one 2GB stick and two 1GB sticks makes no difference to having two 2GB sticks?

 

No notebook has more than two slots. None of the chipsets would support it, from AMD or Intel, AFAIK. I've certainly never seen any with more than two.

 

Its likely that the notebook thats linked, has only two slots. Its most probable that TrustedReviews have made a small mistake on the specifications page.

 

in which they did. The additional 1 gig of memory they are reffering to is turbo memory, described here: http://mostwanted.webuser.co.uk/2007/05/evesham_zieo_n5.html

 

Ah I see. I guess that means I'll be spending an additional £140 buying 2x2GB sticks for my notebook. How likely is it that two different brands of 2GB RAM will not work in dual channel mode? 15-20% sounds like a serious performance loss.

 

Its likely that the brands you by will work in dual channel. If you want an absolute gurantee, then you should look for a dual channel kit, which will have matching modules.

Bear in mind, a 15-20% performance loss will only occur if the processor is under quite a load, and requires memory bandwidth. In applications, where just the processor was under load, the difference in dual channel was 1-5%. Also, if you are not using an 800 MHz FSB, then all the information about dual channel is irrelevant. This is because, assuming your FSB if 667 MHz, and you have 667 MHz RAM installed, your giving the processor the correct bandwidth.

 

I would like to know if I get 3gb (1gb + 2gb) in my notebook, will it run in dual channel mode? Specifically I'm looking into getting a Lenovo T61.

 

No it wont. But you wont notice much of a differance. Dual channel is not that important more ram is more important.

 

Hmmmm... Now I have to decide whether it's worth getting 4gb (2x2gb) in order for it to be dual channel, even though windows 32-bit will probably only recognize 3.5gb of it. I might end up installing 64-bit windows sometime, when it becomes more supported. Or would it be better to just get 2gb (2x1gb)?

 

when i said 15-20% performance increase, i meant it in the "theoretical memory intensive situation" use of the word. you wont see any difference just using the computer, either way.