Jump to content
Corsair Community

Sony laptop detecting new 512mb chips as 256mb. Help!


Recommended Posts

I just purchased 2 Corsair 200 pin DDR SO-DIMM modules to use in my Sony PCG-K33 laptop. However, when I installed them in the laptop it only detects them as 256mb instead of 512mb.


This laptop I guess is supposed to use PC2100 (I thought it was supposed to use PC2700 when I ordered) but I understand that the PC2700 should just run at the slower pc2100 rate.


Any ideas what is going on that the 512 chips are only being detected as 256? I figured if they weren't compatable they wouldn't work at all.


I did try just one of the chips the computer detected it as 256mb still.

Link to comment
Share on other sites

Ok, here I am thinking I'm an idiot because I ordered the wrong RAM for my computer, and trying to figure out where I went wrong. Then I went to put my old RAM back in to send these chips back, when I remembered: the old chips (the ones that shipped with the computer) ARE PC2700 333mhz. So why don't the Corsair PC2700 ones work? Sony's website does say that it should use PC2100, but if the stock chips are pc2700 I don't understand why it wouldn't work with other pc2700 chips?
Link to comment
Share on other sites

It has to do with the density of the memory modules. That is the number of chips per bank. These days memory in the PC2100 and PC2700 realm will typically only work in computer systems that were designed specifically for those standards. I faced the same issue when searching for memory modules for a Dell C600. Older, PC133 SO-DIMMs would be backwards compatible and work at PC100 speeds because they used to be manufactured as low density modules. However, because PC133 modules these days are high density modules, they aren't backwards compatible. So, I was left with having to get true PC100 modules, just as you are left with finding true PC2100 modules. The end result is that both of us are facing increased prices for those modules because of supply being low. What I did was resort to using Ebay to find the memory I needed. I found it, it worked great and I saved around $70.


In essence:


Old PC2700 modules are lower density.

New PC2700 modules are high density.


Typically there is two memory banks per physical memory slot. High density means that rather than a 512MB stick of memory having 256MB of memory per side, and thus per bank, it has 512MB of memory in one bank and nothing in the other. Your computer was designed to expect 256MB of memory per bank. So, when it attempts to use the high density 512MB memory module, it can only read up to 256MB in the one bank, and since the other bank has nothing in it, it doesn't read anything there. Hence, the computer only sees 256MB of the 512MB. You could actually stick a 1GB stick of the high density memory that would have 512MB per bank in the same hypothetical system and end up with only 512MB because because it reads 256MB from the first bank, and 256MB from the second bank. If you were able to get a 2GB stick of memory in that system, it would read only 512MB, 256MB per bank because it can't read more than 256MB per bank, by design. It is a limitation of the chipset used in that notebook because back then, people didn't put as much memory into their systems as they need today.


I hope this all makes sense. You would face the same issue regardless of the memory manufacturer you bought new PC2700 modules from.

Link to comment
Share on other sites

Thanks for the quick reply!


The module is:




other bar code on the memory is: 06460810, UPC bar code reads: 870584001867


I'm trying to resolve the same problem (BIOS recognizes my two 512meg modules as two 256meg modules.) I initially used the same memory you are using, but returned it for the more expensive CMSS512MB-333SOD modules. They too are not recognized correctly by BIOS. So, I would not suggest trying the more expensive modules. By-the-way my machine is a Sony Vaio PCG-K13.


If you do find a fix, I would be grateful if you'd share it with me. I expect the problem is BIOS related.

Link to comment
Share on other sites


This topic is now archived and is closed to further replies.

  • Create New...