Thinkpads Forum

just curious because I don't really understand where the limitations come from- can you override the maximum RAM your system says it will take the way you can override the maximum HDD it says it will take? If so, how? If not, why not?

You usually cannot override the memory limit. The limit is the smallest of the limits of several components. The CPU, BIOS, memory interface controller, physical interface wiring, motherboard design, part availability and other things all contribute to the memory limit.

However, it often happened that when a machine was made that IBM said the machine would take the largest part available, but designed the machine so that it would take larger parts if they were ever made.

My 750P could take a 16MB card when it was new so all the documentation of the day said 20MB was its limit (with the 4MB built in), but somebody made a 32MB card, and with a BIOS update, I have 36MB in there now. The 600E took 128MB parts when it was new, and just after that, 256MB parts became available. A BIOS upgrade lets you use them.

My 600X took 256MB parts when it was new, and its maximum memory capacity CANNOT be increased. The 600X uses the 440BX chipset, and that is limited to so each bank of memory must have 256MB of RAM or less. And no one has ever made a 512MB PC100 low density SO-DIMM for me to test it out with.

I know some 240-series parts can use more than their design maximum if you disable the internal memory.

Which machine(s) do you have?

I looked up your posts and saw one about a 380Z.

As you probably know by now, that machine should use any hard drive up to 136GB or so. Also, it uses PC66 SO-DIMM memory.

BUT, I have a 570, which also has a PII CPU, and uses PC66 SO-DIMM memory. Just for kicks, I took out a 256MB PC100 SO-DIMM from my 600X, popped it in my 570, and it worked.

So, if you can test the memory, and you need more than 160MB (which your parents may well not), you should try that... once you update your BIOS, of course.

And if they plan to use the machine for a while yet, have them get a new battery already... and WiFi too. Make the laptop truly portable.