since everyone is asking memory questions...

[XeonTux]

Here's a question that's been bugging me for a while.

I have a Gateway PII mobo with (2) 64 MB PC66 modules. A while back I tried to upgrade. Since PC66 was no longer available I tried several unbuffered PC100 modules. None worked, neither with or without my original ram installed along with it. I thought PC100 should work in a PC66 application.

The mobo specs state "4clock 66Mhz unbuffered". What does "4clock" mean, and could this be what held me up?

If I had to guess I'd say latency? But I doubt the PC100 was higher...

I no longer plan to upgrade this system, but I would still like to figure this out...for the sake of curiosity I guess.

 

[medic]

I believe there are two different types of ram, the 2clock and the 4clock. The 2clock variety accesses 2 chips on the PCB for every clock cycle and the 4clock can access 4 chips for every cycle. Most current ram is 4clock and I'm quite sure they can't be mixed or if your M.B. requires one you can't use the other. (older 2clock mostly)

Edit:
Found this:

 

[XeonTux]

Thanks for the explanation

I would guess that the new memory I tried was prob 4clock, if most newer memory is. This was within the last year.

Is it possible that my mobo won't take PC100? But that doesn't make sense to me...

 

[divinemartyr]

Memory is backwards compatible. If you buy PC133 memory it will work in a machine which only accepts up to PC100. So PC100 memory should work no problem in your machine. You may have just gotten unlucky and picked a particular chip which didn't work in your machine. Crucial.com is very good about compatibility issues. Put in the type of motherboard you have and it will be able to tell you which types of memory work in your machine.

divinemartyr