Problem mixing PC100 and PC133

S

scarvalhojr

n00b
Joined
Nov 4, 2006
Messages
3
Hi everybody,

I recently bought an original Toshiba PC100 256 MB (PA3069U-1M25) for my old Satellite 1805-S253 notebook - don't flame me, this old lady has a great sentimental value... :) - which already has a 256 MB PC133 SAMSUNG working fine for years.

Both modules work fine in any of the two slots, but only when they are alone -- all of the following configurations work:

Slot 1 - PC133 / Slot 2 - empty
Slot 1 - empty / Slot 2 - PC133
Slot 1 - PC100 / Slot 2 - empty
Slot 1 - empty / Slot 2 - PC100

I performed several tests with all these configurations, so I conclude that not only both modules are fine, but also that both slots are ok.

The problem is that the computer refuses to start when both are installed -- either:

Slot 1 - PC133 / Slot 2 - PC100
Slot 1 - PC100 / Slot 2 - PC133

Does anybody know why?

The manual says I should use PC100, but I know PC133 can also work at 100Mhz, and it should be ok to mix PC100 and PC133, right?

The PC133 (Samsung) did not come with the notebook -- I bought it 2 or 3 years ago. The computer came with an original Toshiba 128 MB PC100 that I no longer have.

Unfortunately, I don't have other PC100 or PC133 to test other configurations. So I guess I have to buy another one, either a Samsung PC133 (which is cheaper) or a Toshiba PC100, so that I can try with two identical modules...

What would you do?

Cheers
 
No flame job here. Some brands of notebooks are very picky about memory. Seems like you have one of those. I found this....

ttp://www.4allmemory.com/index.cfm?fuseaction=search.memorySearch&model_id=22664&memory_id=71068&product_id=71068&product_type=Memory&p=352

Your Toshiba Satellite 1805-S253 only supports modules made with a specific type of chip. Should you find what seems to be the exact same memory elsewhere for a lower price, it is very possible that the cheaper memory will not work in your computer.

By using the 4AllMemory "Memory Finder" your selected memory modules are Guaranteed To Work or your money back!

Maybe the memory you bought and the memory that came with the notebook are just incompatible due to different chipsets. It might sound stupid, but there are different chip densities which affect compatibility. I had similar problems a milion years ago with slot A Athlon and slot 1 Pentium motherboards.

BTW, there are alot of sites to check compatibility, not just the one I found in 30 seconds or searching. Good luck.
 
Waveforme said:
No flame job here. Some brands of notebooks are very picky about memory. Seems like you have one of those. I found this....

ttp://www.4allmemory.com/index.cfm?fuseaction=search.memorySearch&model_id=22664&memory_id=71068&product_id=71068&product_type=Memory&p=352

Your Toshiba Satellite 1805-S253 only supports modules made with a specific type of chip. Should you find what seems to be the exact same memory elsewhere for a lower price, it is very possible that the cheaper memory will not work in your computer.

By using the 4AllMemory "Memory Finder" your selected memory modules are Guaranteed To Work or your money back!

Maybe the memory you bought and the memory that came with the notebook are just incompatible due to different chipsets. It might sound stupid, but there are different chip densities which affect compatibility. I had similar problems a milion years ago with slot A Athlon and slot 1 Pentium motherboards.

BTW, there are alot of sites to check compatibility, not just the one I found in 30 seconds or searching. Good luck.
Click to expand...

Thanks for the comments.

But the funny thing is that the computer works with both modules when they are alone. It just doesn't work when both modules are installed!

So it's not a case of incompatibility between the Satellite and the memory chips, but between the two modules!
 
You could try to see if a newer BIOS will fix the problem, but they are probably just not compatible.

Last time I added memory to an old notebook, I made sure I used the same memory, even if it did cost a little more.
 
scarvalhojr said:
Thanks for the comments.

But the funny thing is that the computer works with both modules when they are alone. It just doesn't work when both modules are installed!

So it's not a case of incompatibility between the Satellite and the memory chips, but between the two modules!
Click to expand...

Sound like you have a high density PC133 and a low density PC100. The system can't differentiate the two when they're in together, so it never gets to POST. High density RAM is addressed differently than low, density RAM.
 
How can I be sure that this is the problem? I never heard about this density stuff... manufacturers don't mention that?

So I guess it should be ok if I buy another Samsung PC133, right?

Thanks a lot for the help
 
I guess one thing you might be able to try is use just one stick. Go into the BIOS and see if you can set any memory speeds/settings. Get them off of auto and set them manually. Longshot but it might keep the system from trying to autodetect what's available and having problems.
 
Density is definitely your issue. Some people will talk about density, build or configuration. They are all the same thing. One poster previously mentioned that your Samsung 133 module is probably high density and your new Toshiba 100 is low density. That is probably the issue. That is why your machine works fine with either alone but "freaks out" when they are together. You need to determine what build your modules are then decide which one you want to keep and find a matching build to install along side it. Since your machine is a 100Mhz based motherboard it does not matter if you decide to keep the 133 or the 100 module. They will all run at the limit of the motherboard, 100Mhz.

If you look at the black chips on the memory modules themselves you will see a string of alpha-numeric characters stamped or etched into them. Usually a simple Google search on this number will produce information on the build of the chip; i.e. 16X8, 8X16, 16X16, 32X8 and so on. Once you know the build of the module you can make an educated purchase on the correct module to install alongside it.

If a Google search doesn't yield any results, I'd do what waveforme said and check out that 4allmemory. I checked them out and they have a great website. Really easy to use.
 
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