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Posted by: mf-2hd on 2015-03-17 09:07:39 Hi, I recently bought a Quadra950 with got four of those memory chips. Installed, all it gives me is a strange start sound and then nothing happens. If I take the memory out the computer starts successfully (there are more, but obviously smaller memory chips in it). I already tried putting only two into the machine or switch memory banks or use another Quadra. But everytime the Quadra won´t boot. Does anyone know the capacity of those chips and any hints on fixing them? Thanks

Posted by: dougg3 on 2015-03-17 09:35:08 I can help with determining the size: The memory chips are GM71C4400, which are each a 4 megabit chip (1M x 4 bit). Each SIMM has 32 chips (16 on each side) so it appears these are 16 megabyte SIMMs. 30-pin SIMMs have to be matched in sets of four in the same bank, so you can't get away with only putting 2 in. You could try cleaning the contacts on the SIMMs, but they might just be bad. If all else fails, OWC sells replacement 16 MB SIMMs.

Posted by: trag on 2015-03-17 14:51:19 Just to reinforce.   I agree with exactly what Doug wrote. Also, these are composite SIMMs, which means that they made a large capacity SIMM out of small capacity chips.   They use more power, and draw more current from the logic board drivers.   Apple recommends against using composite SIMMs in pretty much all of their machines.  Some times they will work.  I had a set just like these in my IIci.   I sold them a long long time ago.

Posted by: mf-2hd on 2015-03-17 14:59:57 Thanks a lot for the informtions. I certainly will consider OWC. And they are cheaper there than I thought🙂

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