Can I put 256MB PC133 in a notebook with 192MB PC66 max?

[Kuroyama]

I have an older Compaq Presario 1920 notebook ("upgraded" to 333MHz PII mobile & 40GB 5200RPM hard drive). It runs Win98, WinXP & Fedora just fine (although a bit slow to boot the latter two) and is fairly compact so I don't feel like replacing it as I normally use my desktop anyways.

I would like to add some memory to this. I've reached the official maximum of 192MB PC66 memory (64MB built-in + 128MB extra). It seems the largest PC66 modules available are 128MB, which might explain the 192MB maximum. However, if I pop in PC133 shouldn't it clock back to PC66 automatically? Would the BIOS recognize a larger 256MB or 512MB module, or might it only recognize the first 128MB?

 

[LED]

It should and there may be a BIOS update...

 

[Kuroyama]

Only one BIOS update and it makes no mention of increasing the allowable memory.

 

[LED]

Worse scenerio is that it won't read and you'll have RAM for your next Lappy...get the fastest as RAM is backward compatible

 

[AsianriceX]

I had the same situation a while back with my Fujitsu laptop. It runs PC100 with 128MB built in, 256MB total max. I bought a 128MB stick of PC133 and it ran fine.

I came across the opportunity to try out a 256MB stick of PC100 and the laptop only detected 128MB of it, which really sucks since I know that laptop would run even better with 384MB.

Now, I won't say that's how it works for all laptops, but this is just my experience with trying to go past manufacturer's limits.

 

[Peter]

Those old 66 MHz chipsets have a surprisingly low limit on how big a RAM chip they can handle. Hence the 128-MByte per-DIMM limit. This isn't about the speed grade at all.

 

[Kuroyama]

Thanks for the info. Checked and found the chipset is the Intel 440BX series. Supposedly supports up to 1GB RAM, although I suppose this doesn't mean Compaq's BIOS will be OK. I'll give it a shot and if it fails then I'll sell the RAM on EBay.

 

[Peter]

Intel BX does 128 megaBITS per chip. So the largest SO-DIMMs you can have are 128 MBytes, made from exactly those "16Mx8" chips that are the largest the 440BX can handle.

 

[Kuroyama]

Thanks Peter. Guess I won't be upgrading my RAM then.