R40 TRUE Max supported memory?

[eddief]

Hi, I have a R40 Thinkpad with a 2.2GHz Pentium 4 M processor.

All the specs I've read state that the maximum memory this machine will take is 1GB - 2x512 DDR PC2700.

I also have an R51 with 1GB DDR (one 1GB memory module). Just as an experiment I tranferred the 1GB module from the R51 to the R40, and to my suprise the R40 booted. Then I added one 128MB the the other slot in the R40, and it worked too.

I also ran Memtest86 (I forgot which version of Memtest86 - if it makes a difference), and it ran one full pass over the 1.1GB memory. Zero Errors.

Will my R40 handle 2GB?
What is the true RAM capacity of an R40?
Am I risking damaging the R40 or my RAM running it with memory that is not officially supported?

Thanks!

[ajkula66]

2GB on all models apart from R40e.

[eddief]

2GB on all models apart from R40e.

Thanks for your quick reply.

I saw this at Lenovo and thought it was the last word...
http://www-307.ibm.com/pc/support/site. ... 45916.html

"Memory 128MB, 256MB, or 512MB and supports up to 2GB maximum memory for Pentium M models (1GB for Pentium 4 and Celeron models) "

I just fuond the thread regarding more than 1GB on the R40, which counters what Lenovo states.
http://forum.thinkpads.com/viewtopic.ph ... 40+upgrade

I wonder why IBM/Lenovo differed on the Max memory for the P-M .vs. P4-M?

[ajkula66]

You've got to remember that when these machines were introduced the largest SODIMM for PC2100 was 512MB, so IBM never updated the records...by the time the final (Pentium M) units were out, 1GB DIMMs were widely available.

If you look at any other P4M ThinkPad of this era (A31/p, T30) you'll notice that the official specs always state that 1GB is max, meanwhile any of them will take 2GB and sing...

[eddief]

Thanks again. I plan on getting a 1GB PC2700 module.

BTW, Is it possible to replace the P4-M with a Pentium-M? Would the battery last longer with the change and other benefits?

AND... I would like to upgrade the BIOS, currently 1.9, but I don't have a good main battery. Is there a reliable way to mod the BIOS patcher to ignore a dead main battery and update the BIOS?

[ajkula66]

You'd need a different motherboard for a PM CPU, which is really not worth it in my book. Even if you were to swap the board, you'd be limited to Banias PM CPUs, with the top speed of 1.7 Ghz and 1MB L2 cache.

I'm not aware of any way of updating the BIOS on R40 with a bad battery. If your machine is running well, an update might not be necessary.

Good luck.