333MHz iMac & 256MB Stick O' RAM

fahlmanfahlman
Posted:
in Genius Bar edited January 2014
My friend has a 15" flat panel iMac that she just had all the original RAM replaced. It had a 256MB SODIMM and a 256MB SDRAM, which she just replaced both with 512MB sticks. I put the SODIMM in to an old 333MHz iMac yesterday but it only appears to onlt be 128MB. It has the latest firmware and OS X. Why isn't working? Thanks.

Comments

  • Reply 1 of 7
    spartspart Posts: 2,060member
    I've had this explained to me before, but I honestly can't say that I remember how it works anymore. In any event, newer SODIMM's wont work fully in older Macs like yours. The computer will be able to see the RAM, but only half of it. This is normal.



    If you buy a stick meant for use in your computer, (like I have) all of it will show up. Not sure if there are any hazards in using newer RAM, but you should probably drop by Crucial.com and pick up a stick. In the past, I've gotten low profile SODIMMS (shorter ones that fit in the bottom slot on your processor card) for no extra charge from them.
  • Reply 2 of 7
    baumanbauman Posts: 1,248member
    I would imagine that the problem comes from the fact that the G4 iMac RAM is 133MHz, whereas the G3 iMac only uses 66 MHz RAM. There is some backwards compatibility, and so that's probably why you're only seeing half.



    Of course, I'm not an expert on this, but that's my opinion. I have both a 333MHz iMac and an 800 G4 iMac, and have installed extra RAM in both. IIRC, the limit on memory size in the G3s was just limited by chip size when they were manufactured. You can put in much more than what it lists as the max, and it will recognize it correctly... as long as it's the correct type and speed
  • Reply 3 of 7
    1337_5l4xx0r1337_5l4xx0r Posts: 1,558member
    Nope. It has to do with the megabit densities of the chips on the RAM module. Older macs can only address so much density per chip. Newer Macs, especially the latest ones, can address much more dense chips. My wallstreet G3 powerbook can only address 16MB per chip per RAM module. So a 256MB sodimm (x2) is the max ram for this machine.



    My Tibook must be able to access 32MB chips on a Ram module, possibly higher, making the RAM limit 1GB (2x 512MB) for now, until memory is made on a smaller process and more can be crammed in (drool).



    A stick of PC133 is rated to run as high as 133mhz, but can easy run at less than that, say 66mhz.
  • Reply 4 of 7
    spartspart Posts: 2,060member
    Not true about your Wallstreet, OWC used to have high profile 256MB SODIMM's that would work in older G3 PowerBooks and tray loading iMacs. I haven't seen them in a while on any websites, but you could try looking around on eBay or doing a less hasty search than I.



    Good to know that about the RAM chip densities (again.) I deleted the email Mike Breeden (the guy who runs XLR8yourmac.com) sent me on the topic.
  • Reply 5 of 7
    1337_5l4xx0r1337_5l4xx0r Posts: 1,558member
    Quote:

    Not true about your Wallstreet, OWC used to have high profile 256MB SODIMM's that would work in older G3 PowerBooks and tray loading iMacs. I haven't seen them in a while on any websites, but you could try looking around on eBay or doing a less hasty search than I.



    I've got one. It has 16 chips on it. They also make a low profile one, which (I'm guessing) is 16MB chips made on a smaller process, crammed on that tiny board.



    edit: I think you misread my post. Walsstreet = 512MB (256 x 2) max.
  • Reply 6 of 7
    spartspart Posts: 2,060member
    Quote:

    Originally posted by 1337_5L4Xx0R

    I've got one. It has 16 chips on it. They also make a low profile one, which (I'm guessing) is 16MB chips made on a smaller process, crammed on that tiny board.



    edit: I think you misread my post. Walsstreet = 512MB (256 x 2) max.



    Actually, no, I read your post fine. My brain is having trouble expressing itself, however. What I meant to say was that OWC used to carry 512MB SO-DIMMs that would work in the Wallstreets and tray-loading iMacs. Thus raising the maximum limit (if you can find one of those modules) to 768MB.
  • Reply 7 of 7
    ghost_user_nameghost_user_name Posts: 22,667member
    Wait this is true because I just ran into this problem...



    I upgraded my Fathers iMac G3 333mhz (rev.d) with a 128mb sodimm pulled from a new iBook. It only came up with 64 of the 128 megabytes. I concluded it was a firmware issue but the iMac was up to date. No loss, I only spent $8 CDN off ebay for the ram. (it now runs a total of 128megs with 64 on the bottom dimm and 128 running as 64 on the top dimm)
Sign In or Register to comment.