[JohnM15141]

Okay,

Lot's of topics in this one question! Any whooo...

In anticipation of the impending release of OS X (and RAM is so damn cheap!) I upgraded my 500 MHZ G4 Cube with two sticks'o 256MB Ram from Crucial.com (shameless plug.) The new memory I got is 2-2-2 while the 128MB chip in my Cube was 3-2-2.

My question is, do I drop the 128MB chip because of stability or speed problems(if they exist) with mixing 2-2-2 and 3-2-2 memory?

With just 512MB of memory installed do I have enough memory installed to dispense with Virtual Memory using OS9.1 while I wait for OS X to arrive?

Should I just mix the chips and get 512MB of 2-2-2 plus 128 MB of 3-2-2 RAM and use some of that space for a really large RAM Disk?

I'd like to know what the prevailing opinions are on this topic is or if someone has a better idea that I could use...?

[Cake]

Mixing Ram won't cause any stability problems, it's just that all the Ram will run at the speed of the slowest chip. So All your Ram will run at 3-2-2 and I've heard that this is about a 4% slow down. I have no idea if that figure is accurate - Just throwing it out there in case someone can confirm or give us the true percentage.

Regarding VM, I've never been a fan of VM, but I know that I can't run my iBook properly without it on. Since I got my G4/533DP I've learned which programs don't like VM, but generally I leave it on and my system is solid. You'll get lots of opinions on VM.

[zigzag]

If you go back to crucial's website and read the FAQ, you'll see that the difference between 2-2-2 and 3-2-2 is NANOSECONDS. Unless you're plotting space shuttle trips for NASA, I doubt you'll notice any difference. I'd leave it all in - 640 MB of 3-2-2 is better than 512 MB of 2-2-2. I have a mix of chips in my Cube and it works great.

Whether it's 512 or 640 MB, I would try turning VM off, and see what happens. Your apps may use more RAM with it off, but you have way more than enough to make up for it. I turned it off on my machine (iMovie doesn't like it) and have left it off and I think my machine runs faster, with no memory problems.

[JohnM15141]

Okay, I went ahead and mixed the Ram so I have 640MB installed.

Incidently, I ran the Firmware update and installed OS X and all is well.

My Cube is running smoothly.

[jenman27]

Virtual memory management is a lot better under OS 9 than ever before... To the point where it is actually a benefit than a liability, especially if you don't have a lot of RAM installed (probably below 128 MB). However, it can't beat real memory, and you have plenty of it... So go ahead and turn off virtual memory.

In addition, you have so much memory now that I bet you won't even be able to use it all at any one time... Unless, for example, you do heavy-duty graphics work or run RAM-intensive programs such as Photoshop where more RAM actually helps the application. For some applications, increasing the memory allocation beyond a certain point doesn't benefit it.

As for OS X, you only really need 128 MB (preferably 192 MB), and some have been able to run it with less than 128 MB. If you're new to this memory stuff and aren't sure how much memory an average user needs, then you can sit back and relax because 512 MB of RAM is actually "overkill" unless you're a power user.

There is no problem with mixing with 2-2-2 and 3-2-2 memory in ANY type of Mac... No stability problems, no speed problems. SDRAM modules are defined by three numbers, such as 2-2-2 or 3-2-2. The first number refers to CAS Latency. CL2 (or CAS2) parts process data a little quicker than CL3 (or CAS3) parts in that you have to wait one less clock cycle for the initial data. However, after the first piece of data is processed, the rest of the data is processed at equal speeds. Latency only affects the initial burst of data. Once data starts flowing, there is no effect.

With all the hype about CAS Latency, just how important is it? In general, the importance is nominal and is humanly impossible to detect, since it occurs faster than the blink of an eye (echoing the previous post about the time difference being in *nanoseconds*). Once again, this is only a concern for those who do heavy-duty, RAM-intensive work, such as those who work with large data files where the difference is anywhere between 5-10%.

There seems to be a general misconception of what those numbers mean. When a person sees that number "3" in 3-2-2 and then notices the "2" in 2-2-2, then he/she will assume that there's a huge difference in terms of the speed. However, in reality, those numbers refer to clock cycles, and as mentioned above, it is a "microscopic" difference.