A question about using both PC133 and PC100 memory...

[Hork]

I've been overclocking my PIII-550E Coppermine to run at 733 by using a 133 bus. Up till now, I've been using a 64MB stick of PC100 memory. I just ordered a 128MB stick of PC133 the other day from Best Buy and it should be at home when I get home tonight.

Can someone explain a few things about memory speeds for me? Is it okay to mix the 64MB PC100 and the 128MB PC133 in the same computer? If I do, will it decrease the performance of the PC133 memory? Is the fact that I'm overclocking going to change anything?

Sorry for the newbieish questions. I appreciate the time and knowledge of the people that post on this board.

Hork

 

[obenton]

You're lucky your PC100 stick runs at all on a 133 bus. should be OK.

 

[Hork]

Anybody have any more detailed information?

If I'm mixing memory will it slow things down as compared to not mixing it?

Hork

 

[Ulysses]

Your RAM's performance is limited to the lowest common denominator among the RAM modules you install.

The 100 in PC100 (and the 133 in PC133) is a minimum, not a maximum. Sometimes manufacturers will label PC133 RAM as PC100 just to meet market demand, and that's probably what you got with that first stick. So it should not slow you down to mix those two types of RAM, since your PC100 RAM is already running @ 133 MHz (which means it is really PC133 RAM anyway).

But do buy good quality RAM such as Corsair, Mushkin, Crucial etc. However, I would not buy the more expensive CAS 2-2-2 type RAM, since you probably will not be able to take advantage of its lower latency. That's because the PC100 RAM you have is probably CAS 3-3-3 (at least at 133 MHz).


You might run SiSoft Sandra to see what your RAM specs are - it may show the CAS latency ratings of the RAM you have and give other interesting info about your RAM and your system as a whole.