New memory fitted, now turning off randomly

eddjedi

macrumors 6502
Original poster
Sep 7, 2011
498
499
I have just upgraded my 27" iMac to the full 16GB RAM. It recognises it fine, however the computer has started rebooting randomly. No warning, it just turns off, and then bizarrely there's no error message when it restarts (in my experience the computer usually knows when it has crashed and offers you the chance to send an error report.)

Here is the exact memory I bought:

http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItemVersion&item=260814559124

It was cheap, but does claim to be good quality. Can anyone give me any ideas as to why the computer just turns off? Are there any error logs I can check?
 

wpotere

Guest
Oct 7, 2010
1,533
1
I have just upgraded my 27" iMac to the full 16GB RAM. It recognises it fine, however the computer has started rebooting randomly. No warning, it just turns off, and then bizarrely there's no error message when it restarts (in my experience the computer usually knows when it has crashed and offers you the chance to send an error report.)

Here is the exact memory I bought:

http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItemVersion&item=260814559124

It was cheap, but does claim to be good quality. Can anyone give me any ideas as to why the computer just turns off? Are there any error logs I can check?
Bad memory.... You likely have a bad module.
 

maflynn

Moderator
Staff member
May 3, 2009
65,429
31,474
Boston
It was cheap, but does claim to be good quality. Can anyone give me any ideas as to why the computer just turns off? Are there any error logs I can check?
defective memory. Take a step back and look at the big picture.

You upgrade your computer and it suddenly becomes unstable. The odds are quite high its bad ram.
 

eddjedi

macrumors 6502
Original poster
Sep 7, 2011
498
499
Thanks for the reply. Is there any way of actually testing which module is bad? Or seeing if the iMac considers it compatible? I want to have some idea of what I'm talking about before going back to the seller and complaining.
 

Consultant

macrumors G5
Jun 27, 2007
13,291
14
Use your computer with 3 chips at a time to figure out which RAM module is bad.