3GB vs 4GB performance on VAio Z series

Hi,

I know that Z-series has dual channel memory controller so does that mean 4GB performance is way better than 3GB? and did anyone check the performance difference between 3GB and 4GB on vaio Z.

Thanks,

 

z series supports dual channel with 3gb too, called asynchronous something, so.. it will offer the same performance

definitely not worth the 100$ add on in my opinion, what i'd recommend is to get the 50$ 3gb option, OR get the 2gb and then go out and buy another 2gb for 50$ (not to mention it's going to be even better ram than what sony provides).. i chose the 50$ 3gb option instead of going out to get 2 gb because the performance gain is negligible and not even worth my time driving to the computer store

 

You need a 64-bit OS to take advantage of the full compliment of 4GB of memory; a 32bit OS will give you 3GB of access (well, just slightly over). Performance is not just memory, but memory + disk I/O + processor.

And how well it all performs is relative to what you do. If you do a lot of things like video rendering and VMWare, you'll need more memory and disk I/O (as well as processor, but the difference, say, between a 2.4 and a 2.53 or a 2.6 won't be as big as a better disk subsystem).

So there's nothing definitive you're going to find.

I find my Z is much faster with Windows 7 64-bit and 4GB of memory than 32-bit Vista and the same 4GB, but able to use less. Also, it helps I have the RAIDed version of the Z with the 2x64GB SSDs.

 

Can the Z be upgraded to 8GB?

 

This is bad advice. If adding RAM, it's better to add RAM that has the exact same SPD specs as the RAM you already have. Adding better RAM is, despite what you might think, not only not going to increase performance, but actually reduce it. If you have two different modules with different timings, both will run at the speed of the slowest one, and symmetric access will be turned off, which incurs a small speed penalty.

Either replace all the RAM, or get a module that is identical to what you have.

Now that the faster 5-5-5-15 DDR3 is available, replacing seems the best choice.

As for 3 GB versus 4 GB, as others said, it doesn't matter much unless you run a 64-bit OS. With 32-bit Windows, you won't get much more than 3 GB usable RAM on a Z, especially not on the 1600x900 models. Anything that's memory mapped will subtract from the max usable memory, including the display mapping, and so will the mapped addresses of any other devices.
The more devices a computer has, the less usable max memory you'll have under 32-bit Windows. The Vaio Z has more than most, with WWAN, modem, fingerprint scanner, TPM, eight(!) USB controllers and ditto number of hubs (even though there are only two USB sockets), firewire, webcam, two card readers and two graphics cards. All have memory mapped addresses, which subtract from the 4GB, so you'll end up with just a tad over 3 GB. Other laptops with less hardware may give you closer to 4 GB, but on the Z with 32-bit Windows, it's rather pointless to buy 4 GB instead of 3 GB.

 

i just assumed that the difference in "symmetric access" being off was negligible don't like to go too deep into technicalities