Well, the more I find out about memory, the more confusing things seem to get. I have a iMac 350, slot-loading CD drive, 512K L2, that came with 64MB of RAM. My system profiler says that I need PC100 RAM, as does the computer's help center and most of the websites I've checked, but some claim that I need PC 133. Local retailers (most with next to no mac knowledge)don't agree on whether or not this might be a problem: some say if the machine's made to handle PC100, it can take PC133 and will simply run it at the lower standard, but a few say that PC133 will not work if mixed-and-matched with the existing PC100 64MB chip. More confusing was the discovery of one- and two-sided RAM. When a few of the retailers heard it was for an iMac, they said I'd probably need two-sided RAM, to match what they thought an iMac already used,and when I asked others they said it really didn't matter. Now, popping the back of my mac, the RAM appears to be only one sided (but all this confusion is making me paranoid, and I'm wondering if it's one-sided because it's only a 64 MB chip, and if it were a larger MB chip it would be double-sided). Now, as far as getting Jaguar running reasonably quickly, will getting a 128MB chip (for 192MB total) do, or do I need to add a 256 (320)? Also, though the system profiler says the computer can take a max of 512MB (256 + 256), some retailers (yes, them again) suggested that there shouldn't be a problem with slotting a single 512 chip into one of the slots (and keeping my original 64). Anyhow, thanks for any help you folks can provide, and happy new year and all that good stuff, Noel

Wow! Sorry to hear you've been spinning your wheels with so much conflicting into. I just went through similar upgrades, and here's what worked for me: I added third-party PC100 RAM to a slot-loading iMAC because that's the way the machine was originally configured (with PC100). You could probably use 133, but claims that you "NEED" 133 are just not true. One of the board's gurus, "pickle" turned me on to "ramseekeer.com" for good prices and reliable memory sticks. Just make sure the vendor specifies that it's memory stick is tested and is guaranteed compatible with the updated iMAC firmware. Unless you've already done so, make sure you've installed the latest iMAC firmware (I think 4.1.9) BEFORE you install "X". Failure to do this could cause serious problems that may require service. When it comes to "X", more RAM is better. "X" is a big OS, and it'll run so much better by loading up on the RAM. You'll want to add 256RAM at the minimum. By the way, all the specs on your machine say you can max out at 1024RAM...two 512 sticks. Hope this helps

Sorry...one last thing. Yes, you CAN add a 512 stick and leave keep your original 64. I installed this same upgrade and my machine runs great with 576RAM!

NWC, Sorry...I mispoke about the max RAM. The UPDATED iMAC 350, also blue ("indigo"), is the one that will accept two 512 sticks of memory. The older 350 can be expanded only to 512MB. More info at : everymac.com lowendmac.com

My internet went down for a few days, so (a belated) thank you, Radioboy.

Thx for the kind words, radioboy. That pretty much covered it :) p