Is 4GB better or worse than 3GB on SZ680 with 32-bit Vista?

I searched multiple forums and could not find a definitive answer whether installing 4GB (2x2GB) of RAM in a notebook (with 2 memory slots) is better or worse than just 3GB (1GB+2GB). For example http://www.dansdata.com/askdan00015.htm

Opinions seem to be mixed and some even say that putting 4GB will actually make it worse than 3GB.

I understand than 32 bit OS will not see much RAM over 3GB, so the total amount of RAM available to the system is pretty much the same in both cases. At the same time installing 2 identical 2GB memory modules enables dual-channel memory operation and a little performance boost (maybe just 5% but still an improvement...)

If money is not the question then:

1) which configuration is better: 3GB (1GB+2GB) or 4GB (2x2GB)?

2) will I stiil benefit from a dual-channel performance improvement even though software does not see more than 3GB? (as I understand OS has nothing to do with the dual-channel mode as it is handled by the hardware memory controler and always gets enabled when 2 identical memory modules are installed)

3) has anybody done any 3GB (1GB+2GB) vs 4GB (2GB+2GB) performance comparison?

4) will my SZ680 benefit from PC2-6400 (800MHz) RAM compared to the standard PC2-5300 (667MHz)?

5) those who have 4GB in your SZs, how much RAM does Vista show?

Thanks.

 

I'm a i1520 owner so some of my stuff may differ for you...

1. I went with the 2x2GB for my i1520 due to Dual Channel support... 5% is a nice performance increase to have imho...

2. Yea you'll still get Dual Channel even in a 32bit setup. My computer is currently running Vista 32 bit... I have 64bit loaded in VMware to test before I make the leap...

3. Sorry I didn't do that...

4. Unless this is some super high end notebook I doubt it would have any use for DDR2 800 as the Intel chipsets top out of DDR2 667... Even the new Santa Rosa based ones like in my i1520...

5. Sorry just the i1520 here... Though on my i1520 it sees a bit over 3.5GB...

My thoughts are to go with the 4GB setup... Can never have to much RAM and you'll make the 64bit leap soon enough

 

There are many threads answering this question. Do a search.
In brief there will be almost no difference at all (less than 3%). With the 4gb config you will have all the memory running in DC (but you will be able to use only 3.3GB) and with the 3GB config you will have 2GB in DC and 1GB in single.

 

the SZ680 is a relatively new product, and it should be able to recognize 4 gb of ram. Nearly all desktop motherboards that come out nowdays support up to 8GB of ram.
I believe you need 2 dimms of the same size to have it run in dual channel.
And sony offers configurations available with 4 gb's, so most likely yes.

As far as the pc2-6400 vs pc2-5300 goes, I think it depends on the motherboard. You can overclock it, but I wouldn't recommend any kind of overclocking on a ultra-portable notebook. I would stick with the 667MHz because the 800MHz won't make a huge difference anyways.

I'm giving semi-knowledgeable advice, so if you want to get the best performance, I would wait for more advice, but I know for certain that 4gb of 800MHz ram will work on the laptop, and that you can only run memory in dual channel if they're the same size.

 

this is not correct as I have explained many times in this forum

to see all 4gb you need a 64bit os, cpu and compatible chipset. If our friend has a 64bit OS already I would recommend 4gb.

 

I would like to know the answer, too. So I just did some research...

it's NOT necessary to have two memory chip with the same capacity...
you can still run in dual channel with 1GB+2GB...
so no need to have 2x2GB...it's only useful when you have both dual core CPU AND 64bit OS

some good sources:
http://www.techspot.com/vb/all/windows/t-49943-Dual-Channel-Ram-question.html
http://support.microsoft.com/kb/929605
http://www.eggheadcafe.com/software/aspnet/28817556/-how-much-memory-can-v.aspx

 

glad I found this thread, perhaps someone could help me out.

I just received a VAIO SZ-680 with 4GB or RAM installed. I realize that WIndows cannot make use of >3GB, but I was surprised that my BIOS only shows '3072 MB'. Does this sound correct? Is the graphics card,etc. really siphoning off almost 1GB before the BIOS even? Windows shows the same 3072MB, although VAIO Central shows 4 GB.

I'm confused, any insights?

 

It's correct, but it's not the graphics card taking away memory. The Vaio BIOS cannot recognize more than 3GB of memory (Dell recognizes 3.5GB, some others are in between). Vista can recognize 3.5GB in most 32-bit applications, while 64-bit recognizes all 4GB.

The Vista may see that there really is 4GB installed, but it can only use 3GB of the memory. That's 3GB total for Vista resources and graphic resources.

 

I have sony vaio sz680 T7500 with two 2GB 667 Crucial RAMs but my laptop only shows 3070mb.

 

800mhz ram isnt supported, it'll be scaled down to 667mhz

and once again, 32bit os's can only see ~3.2gb of ram. only 64bit os's can use 4gb and more

 

just add /PAE in your boot.ini and you should be able top recognise any amount of RAM so long as the BIOS does.

 

the bios wont recognize 800mhz ram.

just because the fsb is 800mhz doesnt mean 800mhz ram is supported

 

If you plan on buying RAM and you don't know whether to buy 3 or 4GB or 667mhz vs 800 mhz. I would go with what can be used in the future along with right now. 800mhz(PC2 6400) 4GB of ram which can be found on newegg for a nice price (it had a $10 rebate as well) http://www.newegg.com/Product/Product.aspx?Item=N82E16820227251

 

so lame the sr chipset doesn't support 800mhz ram...

 

Do you know if this also applies to the SZ6 BIOS, and would a firmware update be able to let the BIOS see the whole 4GB so the laptop could use it all when running a 64-bit OS? Also, anybody managed to get their SZ6 to fully recognise 4GB?

 

On Vista x64, the full 4GB is recognised. Sony has posted 64-bit drivers for selected models, but they do not provide any support. I've almost everything working on the SZ650 except the webcam.

 

Yea I know Vista recognises it...but the BIOS still says 3GB...so I'm asking (as in the vista 64bit ftp thread) whether this means that the full 4GB will actually be used or not... Why is the BIOS listing 3GB and not 4...

Btw good luck on getting the webcam working, I'll go hunt for webcam drivers as soon as I have some more spare time next week.

 

Sony really should have more updates on our SZ BIOS. There is no BIOS update from the day one.

 

From CompTIA A+ Guide to Managing & Maintaining Your PC, sixth edition, p. 279.

So unless there is something unusual about this particular laptop, I'd say the RAM sticks DO have to be the same size.

 

so if you're purchasing a new system why wouldn't you get the 64bit OS?

 

Sony doesn't offer a choice of a 32 or 64-Bit OS. They include 32-Bit by default, and do not accept requests for 64-Bit.

Take a look at the following Dual Channel guide and threads to get a better understanding of 2GB+1GB VS 2GB+2GB.

Dual Channel Guide
http://forum.notebookreview.com/showthread.php?t=167472&highlight=dual+channel

Threads:
http://forum.notebookreview.com/showthread.php?t=210129&highlight=dual+channel

http://forum.notebookreview.com/showthread.php?t=209935&highlight=dual+channel

 

4 GB is fully recognized and used by Vista x64. I can get the webcam to work in a round about way, there is no substitute for a real 64-bit driver though.

 

AFAIK...if the bios does not recognize the amount of RAM installed, the OS whether 32-bit, or 64-bit will not be able to use any existing RAM over the amount the bios reports. I just installed 4Gb in a Sony VAIO SZ VGN-SZ360P/C and the bios reports 3072 installed (Corsair 2x2Gb DDR2 667mhz pc5300 SODIMM's). The system boots and runs fine (dual-boot XP professional 32-bit, and Ubuntu 7.10 (Gutsy Gibbon) 64-bit), but sees and uses only 3GB of memory for both OS's. The Sony site did actually have a bios upgrade for this model, but finding it was NOT trivial. (Try: http://esupport.sony.com/US and select your model, then (locate your model / drivers and software / and select XP for the original OS and Vista Business on the Install another Operating system TAB)... and even after the BIOS update, the system still only sees 3GB of installed memory...oh well, I did get it at a pretty good price $80.00 USD and I do get 3GB of usable memroy instead of 2GB - good for my VMware workstation stuff. Maybe the next bios update will allow access to the fully installed amount of memory.

It is interesting, that the VAIO Support Central / System Information utility reports System Memory as 4GBytes...hmmm

 

For what it is worth:

Windows XP/Vista 32 bit cannot use more than 3-3.2 GB of memory, this has been discussed in the forum many times before!

The Sony SZ360P/C uses the Intel PM945 mobile chipset, as per Intel specification, it can support up to 4 GB of memory, but it has a 32-bit interface to address a maximum of 4 GB of memory address space. ftp://download.intel.com/design/mobile/datashts/30921905.pdf

The Sony SZ6XX uses the Intel PM965 mobile chipset, as per Intel specification, it can support up to 4 GB of memory, but it has a 36-bit interface to address a maximum of 64 GB of memory address space. ftp://download.intel.com/design/mobile/datashts/31627303.pdf

As per Microsoft KB929605, for Windows Vista to use all 4 GB of memory on a computer that has 4 GB of memory installed, the computer must meet the following requirements: • The chipset must support at least 8 GB of address space. This basically excludes the PM945 chipset based system even though it can support 4 GB of memory.

 

For what it is or it is not worth.

Go with a 4GB same type sticks 2x2GB and get the fastest you can find.

By running them at 667, your latency will drop and you will avoid any compatibility issues.

As for Vista. You've just lost 30% of your performance just by running it, so performance wise, it doesn't matter if you are with 3 or 4GB

Ditch Vista and go XP/32 or XP/64 if you can do the install

 

An additional note to my previous post, please download the excellent Process Explorer from Microsoft http://technet.microsoft.com/en-us/sysinternals/bb896653.aspx

Go to the Process Explorer System Information page (ctrl + I), the amount of Committed Memory (2nd graph) + Available Memory + System Cache = Total memory Vista is using.

 

or, he can ditch vista for good

 

Question for aralos1999.
Thank you for the good information in this thread aralos. Can you give a reference that explains how you got the above Total Memory formula? This formula is not at all obvious, at least to me.
For an SZ-260 (with XP SP2), we installed 2x2 GB and got similar results as described in this thread: The BIOS says 3072MB, System Properties says 3.00 GB, and Vaio Support Central says 4 GBytes.
The Total Memory formula above, using Commit Charge Current (K) instead of the graph value, gives around 3.4 - 3.5 GB for light and heavy loading (i.e., the sum stays almost constant) (using 1 GB = 1024 MB, 1 MB = 1024 KB, and 1 KB = 1024 bytes). If the formula is correct, then Windows actually is using the expected amount of memory (around 3.4 GB).

 

The best way to find out how Vista is using and how much physical memory you have in your computer, go to Alex Ionescu website and download his excellent meminfo tool.

Alex website: http://www.alex-ionescu.com/

Meminfo download: http://www.winsiderss.com/tools/meminfo/meminfo.zip

Open a command mode window, type meminfo -s

make sure you are running the x64 version.

 

Really? Got some PROOF to back that up? Recent tests with Vista SP1 are saying that is not the case at all. One more thing. Tell us how much memory the 32bit version of XP can reference.

Gary