My T1090 isn't recognizing the (2) 256 MB Modules installed. I am trying to get the max ram at 512 MB. It only recognizes 1 - 256 MB Module and 1 - 128 MB Module (old) at the same time. If both n

Yes you can, at least to 1 Gb maybe possibly to 2 Gb.
There will be two memory slots in your laptop. To increase the RAM to 1 Gb install another 512 Mb RAM module in the empty 2nd memory slot. Make sure you use the same make and speed RAM as the one that is installed.
If you have two 256 Mb RAM modules installed in your laptop then you need to replace the two 256 Mb RAM modules with two 512 Mb RAM modules to get a total of 1 Gb RAM.

Yes you can.
For 512 Mb RAM you can use a single 512 Mb memory module or two 256 Mb memory modules.
For 1 Gb RAM you can use a single 1 Gb memory module or two 512 Mb memory modules.

Simple test - leave only the 512 stick and go into the BIOS and see if the memory is correctly recognized. If it isn't then it's defective. If it is then download, burn and boot from
http://www.pclinuxos.com/
and run the memtest to be sure. If the memory is ok then you will have to reinstall Windows - it doesn't like the new memory.

Hi there
Your t1090 will only accept a maximum chip size of 256Mb and so it will not accept the added the 512mb chip as it cannot handle it. 512 is the maximum size of RAM for this machine but unfortunately you cant put it in in one go

Hi,

Make sure that you got the right memory module with this specs:

Memory

• DDR266 (266 MHz) so-DIMM 200 pin
• 2 DIMM slots; upgradable to 1 GB total memory (512 MB x 2)

or better go to this link http://support.fujitsupc.com/CS/Portal/supportsearch.do?srch=GUIDES

there's a step by step troubleshooting for memory modules. Also make sure you purchase memory module from Fujitsu or Authorized Fujitsu Dealers .

You can also find us over the web, visit us at www.fujitsu.com or for Around-the-Clock Expert Technical Support you may contact us at :
Phone Support (Direct to Service Desk)
1-800-8FUJITS (1-800-838-5487)
Available 24 hours, 7 days a week.
Consumer Sales - 1-800-FUJITSU
Corporate Sales - 1-800-831-3183
Tech Support - 1-800-8FUJITS /1-800 8385487 or 1- 888 -3854212
-ERNZ

Swap the modules between the slots.

If the message shanges to slot 0 not recogonized, then you have a bad memory module,
Easy fix, just get another module.

If the message does not change, then you have a problem on the mother board.
Not an easy fix, it would be cheaper to buy a 1GB module and use the good slot.

Good Luck!

The original 2 sticks of 256 Mb of RAM gives you a total of 512
Mb of RAM. Two 512 Mb of RAM gives you a total of 1 Gb of RAM.
With two sticks of 512 Mb of RAM are you sure you got a total of 192 Mb of RAM, this is a lot less than the original RAM total of 512 Mb?
Should this be 1920 Mb of RAM?
If this 192 Mb is correct then the RAM modules are either not compatible with the laptop or if the RAM modules are not from the same manufacturer then they may not work together.

Most laptops have video cards that use part of the main RAM for video RAM, that is why the available RAM is less than the installed RAM modules. The amount of RAM the video card grabs depends upon the type of video card and in some cases the amount of video RAM can controlled in the BIOS setting.

I am sure when you say 256k you mean 256 mb? You should not have to do anything for the computer to recognize it. Almost all computers are set up to automatically recognize memory. When installed and you right click on my computer and select properties how much ram does it say is installed? If it is just shy of 1GB or if says something like 985MB then that would be normal. If it only says 512 or 469MB then you have a problem with the second memory bank.

visit vaio manual in
ftp://ftp.vaio-link.com/pub/Manuals/Notebooks/
You can do this in two ways: opening your notebook and taking a look on the memory modules already installed (we will explain more about this later) or running a program like Everest (available on our download section). We ran Everest (going to Motherboard, Chipset, Memory Slots) on our notebook and found that it was using two 256 MB DDR-SDRAM PC2700 (“DDR333”) modules, for a total of 512 MB.

click to enlarge
Figure 1: Checking your current memory configuration with Everest.
If your notebook has an empty memory slot, just go to the computer store and buy a new SO-DIMM module with the same technology (SDRAM or DDR-SDRAM) and speed of any capacity you want – of course you need to know the capacity limit of your notebook. You cannot install a 1 GB module in a notebook that only accepts modules up to 512 MB, for example. Our notebook – a Sony Vaio PCG-V505ECP – accepts modules up to 1 GB, for a total of 2 GB RAM, since it has two memory slots.
For example, if your notebook has one 256 MB module and an empty memory slot, if you buy and install another 256 MB module, it will have 512 MB RAM. If you buy and install a 512 MB module, your notebook will have 768 MB.
If your notebook already has two memory modules, you will need to remove one of the installed modules in order to install the new one. If the two modules have the same capacity, it doesn’t matter which one you will take away, but if they have different capacities, remove the one with smaller capacity. The new RAM capacity of your notebook will be of the capacity of the remaining module plus the capacity of the new module.
In our case, our notebook has two 256 MB modules. So we will remove one of these modules and install a new one on its place. We bought a 1 GB-module, so after installing it our notebook will have 1,280 MB RAM installed (memory math is tricky, since 1 GB equals to 1,024 MB not 1,000; so 1,024 MB + 256 MB = 1,280 MB).


else visit
http://www.hardwaresecrets.com/article/189/1

the memory is dual channel, so you have to use matched memory for it to work 1gig in each slot if possible, check the 1 gigs and 512's to see if they run at the same bus speed, if they are not matched there is your problem try a gig and a 512 in slot 0 to see if it picks the memory up, also there is sometimes an option in the bios to dissable dual mode