|It took me a while to make response 4.|
Your response 3 was not here before I started making what became response 4.
According to what you said in response 3, what you said in response 2 was NOT correct....
"The 2 sticks are identical."
"Part #'s are the same."
What you're supposed to do is use a "memory configurator" or similar on a ram manufacturer's or ram distributor's web site to find memory that is compatible with using it in your specific model, by using your specific model to search with, then you can use the ram manufacturer's part number (if it's listed) of the module to search the web or locally and buy them from any place on the web or any local place that lists or has that part number,
OR, you search the web using something such as your specific model and memory, e.g. Satellite A110 st1111 memory or memory upgrades. An example of a result from searching that way is at the end of response 4
(In this case the Kingston and Crucial web sites DO NOT list your A110 st1111 model. They list newer A110 models but the results of searching with that does not list PC2-4200 modules.)
You said in response 5...
"I googled memory upgrade and chose Kahlon because they had the cheapest price."
They DO have......
Kahlon Memory Configurator
The result for....
Toshiba Satellite A110-ST1111
1GB Memory (PC2-4200, DDR2-533MHz) KTT533D2/1G, PA3411U-2M1G
You DID NOT buy that module !
When the part number of a module you're trying to use is NOT listed for your specific brand name system model, or desktop retail mboard model, then there's no guarantee it will be 100% compatible with using it in your mboard when it's installed by itself, or when it's installed along with other modules.
It MAY work fine, but it MAY NOT !
When you have bought the ram, you may be charged a re-stocking fee if you return the ram if it's part number is NOT listed for your model somewhere on the web.
KTT533D2/1G is a Kingston module. It's been discontinued and Kingston no longer has any specific info about it. If they did, they usually have a *.pdf file for their modules that don't have brand name specific part numbers that tells you how many chips it has on it.
When you see pictures of ram modules on the web, they often DO NOT show you whether they have chips on both sides of the module or on just one side, and the text description usually does NOT tell you how many chips it has in total. The Kingston web site is one of the few places where you CAN find out if it has chips on both sides, if they have that *.pdf file for the module.
In most cases, if you know the brand and part number for brand name ram modules, wherever you got the module from, you can go to the memory brand's web site and find out if it's listed for your model by using their ram configurator or similar.
However, I don't think I've ever found a Samsung memory configurator on the web. There are lots of them for whatever memory brand for Samsung laptops and notebooks however.
When you search this way for memory...
"...you search the web using something such as your specific model and memory, e.g. Satellite A110 st1111 memory or memory upgrades. "
..... if they list a specific brand of module, e.g. Samsung, the brand's, e.g. Samsung's, part number of the module is often NOT shown, but whatever module they list is guaranteed to be 100% compatible.
It's likely that either one of the 1 gb modules you bought is not 100% compatible with using it in your mboard, the other one is,
or it could be BOTH of them are not 100% compatible with using it in your mboard.
Obviously they're not 100% compatible with using them in your mboard when both of them are being used in your mboard at the same time.
I'm guessing that both 1 gb modules need to have 8 chips, since the 4 chip 256 mb module's capacity is recognized fine, whether installed by itself or along with another module, and it probably has 1/4 the memory density per chip in comparison to the 8 chip 1 gb module. That's evidence the mboard recognizes lower memory density per chip individual chips fine.
The number or chips in total on the module is only relevant if the modules have the same total capacity.
When the total capacity is the same, usually modules with twice as many chips have half the memory density per chip on the module than ones with half that number of chips, but there are exceptions.
E.g. In rare cases, the way the chips are wired up can make the modules with 4 or 8 chips on one side be detected as if they had twice that number of chips, half the memory density per chip.