2012 iMac (27 inch) will accept 24gb ram, not 16gb ?

[H.Finch]

Hi all,
Quick technical question... I've bought 16 GB of Crucial ram for my iMac... Installed it (removing the standard 2x 4 GB of Apple ram that was in there) and It only made beeps after I clicked the power button...


Then, after a quick Google search I put back the Apple Ram in the first two slots, inserted the 2x 8 GB of Crucial ram in the upper two slots and now it works... with 24 GB.... (see screenshot)


I’ve always thought mixing Ram GB-sizes and manufacturers was a bad thing. But this is the only config in which the iMac even boots up :S


Isn’t this weird? Is there anything bad about having 24 GB of ram, mixed manufacturers the way I have it now? I thought it was all very strange…

Any insight would be very appreciated...

*PS. Wouldn't (in the screenshot) two times 8 GB on the first row, and 2x 4 GB on the second row be better/perform better? Or is this just my OCD acting up?

 

[darinzook]

My Mid-2011 iMac has 24GB of RAM. Has run fine that way for a few years. I'm not sure of the iMac bank layout, but my experience is that you always want to put like sized dimms in the same bank. So 2 8GB sticks side by side, and 2 4GB sticks side by side. So your PS at the bottom would be accurate. Top row would show 8x8 and bottom row would show 4x4.

My experience on hardware is more server based than anything else. Mixing manufacturers of modules isn't really an issue in my experience. You just want to make sure that the memory is the same speed, and that its like-sized in pairs. On a server, I'd install my largest DIMMs closest to the CPU, and cascading smaller the further from the processor you get. I don't know that this actually applies on a iMac tho...

 

[H.Finch]

Thanks Darinzook, for your perspective. Maybe I'll move things around a bit... It all seems to work fine, however my iMac's fan does seem to make more noise then before (I've never heard it in the past 4 years actually)...