Problem with Thinkpad x20 ram

[yoLNEr]

I bought a 256mb stick of pc133 SDRAM to upgrade my x20 but its only being recognized as 128mb. I updated the bios but nothing changed. The max supported ram is supposed to be 320mb. Is this happening because im using pc133 memory instead of pc100 or is it a problem with the mobo?

[Trav2003]

I had the same problem with my old Latitude CPxH, I bought pc133 really cheap on ebay, and it didn't work.

I know my laptop needs pc100, but I just assumed it was backwards compatible with pc133.

Now I did notice it didn't have RAM chips on both sides like the other ram, so it was 4x32 or whatever, instead of 8x16 like the other.

[Abe Froman]

Most laptops, especially IBM have strict requirements for the type of memory you can use - contact the manufacturer or look on their website to be sure.