iMac Frustration

[bjarvis]

The 512 MB SoDIMM for my iMac (15" flat screen, 800 MHz) arrived this afternoon.

According to everything I read, I should simply be able to pop out the 256 MB DIMM in the easily accessed socket in the bottom of the iMac and insert the newer 512 MB DIMM: the memory should be recognized instantly when the machine boots.

No such luck. The machine only recognizes 256 MB of the new 512 MB DIMM; with the already installed 256 MB DIMM in the internal slot, my machine still has only 512 MB instead of a proper total of 768 MB.

I'm still searching Google for ideas as to what might be happening and/or how to fix it, but my suspicion is that the installed DIMM isn't actually appropriate for this architecture. It's that or the beast doesn't like mixed density RAM.

Any ideas? I'm open to any suggestions.

Comments

[abqdan.livejournal.com]

I'd disassemble, remove the other 256 chip, and just leave the new one in place. If the machine then knows it has 512, the problem is a compatibility one; if the machine only recognizes 256, then the new chip has a problem. Although I only work with PCs, I constantly have problems with memory chips that refuse to play nicely together, so I understand the frustration.

[bjarvis.livejournal.com]

Yeah, I'm kinda leaning towards disassembling the beast, but it is serious surgery on this model... I'm not looking forward to it. Still, I'm running out of options. sigh

[excessor.livejournal.com]

Any ideas? I'm open to any suggestions.

The mind boggles.

1. Get a PC. I hear they're running that lovely Vista these days.

2. Lay down on your back…

[bjarvis.livejournal.com]

1. Get a PC. I hear they're running that lovely Vista these days.

I'd rather chew my own foot off.

2. Lay down on your back…

Now you're talking! :-)

[kent4str.livejournal.com]

If you're buying a PC you should lay down on your stomach...

[chrishansenhome.livejournal.com]

I like both PCs and laying down. What does that make me? :-)

Seriously, I think you need to do the surgery. You might also try Crucial's online chip tester (www.crucial.com, I think). That might tell you something about what the Apple thinks is in each socket.

[jwg.livejournal.com]

What did About This Mac say was in each of the slots?

Did you try swapping the two DIMMs to see if that made a difference - it shouldn't?

Call the vendor from which you got the memory.

The previous G5 iMacs happily accepted different sized DIMMs (I have a 1 Gig and 512) in mine although the specs say it runs faster if they are both he same size.

[bjarvis.livejournal.com]

"About this Mac" says that both slots are occupied by 256 MB of RAM. I tried booting with only the internal DIMM and it truthfully reported having only 256 MB total in one slot. Inserting the 512 MB into the empty slot yielded an increase of only 256 MB again.

I haven't tried swapping the internal & accessible DIMM. Getting to the internal DIMM in this model is a very intricate and painful process --imagine replacing your car's air filter by disassembling & reassembling the transmission-- so that's an act of last resort. It's so painful that I'm considering simply send back the RAM and living with the 512 MB I already had: the sluggish performance is less hurt than surgery on the box.