Any reason why pc133 should not be backward compatible with pc100

[Mojonba]

A friend of mine is upgrading his PIII 500mhz laptop ram. I checked the memory specs and it uses PC100 Sdram Sodimm. He went to Compusa and bought a 256 PNY stick but pc133 instead of pc100. I checked on PNY website and it has this disclaimer stating that they are not backward compatible due to higher density chips. I say that disclaimer is BS, but im not sure. What do you guys think?

 

[n7]

Try it.

With older motherboards, using the wrong spec RAM may not work, but trying can't hurt.

 

[Arcanedeath]

PNY is correct, older chipsets will not work w/ higher density memory (or will only detect 1/2 of the memory) and you need to use low density memory in older intel / sis chipsets.

 

[raincityboy]

Manufactures want to sell as much as possible. If they put out an advisement, like this, they usually have their reasons.
Have you tried it?

 

[LTC8K6]

The disclaimer is essentially correct. Newer PC133 and even PC100 modules are high density and older boards may not read them properly.

It won't hurt anything though. I think it will either not boot, or read the high density stick as half it's true size.

 

[Mojonba]

You guys were right, I tried it and it recognized it as half its true size. I exchanged it for a Pc100 and it worked perfectly.

I believe this happended beacuse of industry standard's not being strict enough. I thought that the pc1xx specification was a memory clock speed (mhz) specification and it just meant chips that were designed/handpicked to run at higher mhz but could always run at lower clock speed.