Is DDR backwards compatible?

[Nocturnal]

Installed 1GB into an older Preario 1500 and now it blue screens. I removed the old memory and it says PC2100. I have always thought that DDR was backwards compatible in that PC2700 will downclock to run at PC2100 speeds. Or are there certain memory brands/sticks that are not made to do this?

 

[Quiksilver]

OEM machines built by HP, Dell, Compaq, and others are usually very picky about what memory it uses and probably won't let you use any old memory(which normally would work like you said), you probably need to find the speed of the memory it supports and memory brand it will work with.

 

[Mondoman]

I see two possibilities:
1) the notebook's chipset can't handle a 1GB module.
2) as QS says, the module you tried may not be compatible, even though in theory it should work (you are right about the backwards compatibility).
Since the old module was PC2100, it must be a *very* old notebook; perhaps the pc2700 module doesn't include pc2100 speed setting info in its SPD; if your notebook BIOS allows manual setting of memory speed/timings, you might be able to work around that, but very few notebook BIOSs have such modes.
Many memory vendors have online "configurators" that tell you which of the modules they sell will work with your notebook, and back this up with a money-back guarantee if it's not compatible. You might try buying a module from such a vendor.

 

[Nocturnal]

Just an update, I am truly an idiot. I left Memtest in his CD-ROM drive and sure enough it boots to a "blue screen" and then runs a test. If I had read his text message a bit more clearer instead of panicing, I would not have been put in this situation.

This is hilarious. At least I know the memory is okay. It ran Memtest for 24 hours+ 🙂

 

[magreen]

That's a new one.