[mala]

Hi,

just put in another 256 MB SDRAM next to the other one in my iMac 450 DV+ running Mac OS X 10.3.7. What I thought was a pc100 SDRAM is actually a pc133 SDRAM according to the System Information utility, but the mac itself doesn't complain about it and recognizes all 512 MB or RAM. Am I okey here with this faster memory or am I begging for trouble?

TIA

/Mala

[discotronic]

You should be fine. PC133 is backwards compatible so it will automatically work like PC100.

[mala]

Ok, that's more or less what I was thinking myself. So I won't run into some strange application behaviour in the future because of this?
Another question; I've got a pc133 SDRAM module that's called ECC at the end. What does that mean and can I use it in my iMac 450?

[mala]

With the 512 ECC RAM installed the iMac didn't even boot.

/Mala

[Leonard]

ECC RAM is Error Correction Code RAM which is used mostly in servers. Macs (except for Xserves) use non-ECC RAM. ECC RAM has extra circuitry to validate the contents of the RAM.

[bradoesch]

Originally posted by mala:
Ok, that's more or less what I was thinking myself. So I won't run into some strange application behaviour in the future because of this?

No problems. I've got dual 512 MB PC 133 DIMMS in my iMac DV and everything is happy. They clock down to 100 MHz to match my iMac. They would also slow down to 66 MHz if put in that type of machine.

The only thing I can't figure out is why they still produce and sell PC100 RAM when PC133 will work just fine. Clearing out old inventory? I've seen Futureshop selling identical DIMMS but change more for PC100 over PC133. ???

[chabig]

The speed of the memory tells you how fast it can deliver data. PC100 RAM can operate at 100MHz so that means it can deliver data 10 nanoseconds after the processor gives it the address. Memory that's faster than 100MHz can deliver the data quicker, so when the processor goes looking for the data, it's ready. That's why you can always use memory faster than the minimum specified.

Chris