01-25-2012, 10:27 AM

I purchased a brand new Mac Mini about a month ago, an i7 2.7GHz. I purchased it with 4g of ram and purchased on the side 8G of ram by Corsair (DDR3 1333 SODIMM modules, 9-9-9-24). I purchased the "Mac Memory" version of these sticks. Put them in (super easy) and all is well, or so I thought. On my first backup with Time Machine, hard lock. Second backup, hard lock. I never could get a good backup. I ignored it for then. I then went into iMovie. Working on a project for more than 20 minutes results in a hard lock. So, I put the old 4G ram back in and everything works great, no hard locks.

I put MemTest86+ on a USB drive, put the 8g ram back in and booted. It gets through one full test successfully and then hard locks 1/2 way through the second test. Bad ram I figure.

I purchase a different brand, Centon. DDR3-1333 8G SODIMM modules (unsure of the CAS rating). Put the sticks in, everything works great. I did a full Time Machine backup just to test, and did some heavy video editing just for the fun of it, no hard locks, yay! Then about 3 hours into using it, the screen goes gray and I get the OS X "You must reboot" message. Rebooting yields 3 beeps and black screen, 3 beeps, etc... I popped the bottom thinking that maybe one of the sticks was not fully seated (I admin hundreds of computers and have installed countless number of memory modules but one can always make a mistake!). Everything seemed fine, but I reseated them for the fun of it. Same thing, 3 beeps. Nothing I do makes that memory work again. I read where resetting the NVRAM could do the trick, I reseated the memory, I cleaned the contacts, still 3 beeps.

I put the trusty 4g that came with the mac back in, everything works fine. At this point, I put the Corsair back in (that I think is faulty) and ran the Apple Diagnostics (D) tool 3 times with extended testing turned on. It found no problem. I thought maybe the NVRAM reset trick that I learned may have made this ram now work. So I started OS X, ran iMovie and in about 10 minutes, hard lock.

So... in the end I have tried Corsair Mac Memory and Centon memory (non-mac version) with no luck. One is unstable, the other doesn't work.

I know it is possible that I got two different packages of bad sticks but unlikely. The nearest store that sells this stuff is an hour away, so I'm not sure I want to go for a third try.

Any thoughts? About handling the ram, I do know how to handle it and the original 4G that I have swapped in and our quite a few times now works great, so I don't think I am zapping the memory or anything. I've handled the original 4G twice as many times as the new chips and they are great. Oh, I am using OS X 10.7.2, but I don't think that has anything to do with it as I have lockups in MemTest86+ that I booted into (i.e. no OS X software loaded at all).

Thanks for any help,

Jeremy

01-25-2012, 10:52 AM

I'd ask if you tried reseating the second set of failing ram, but man.. it passed POST once, ran for a while then failed to IML. That will generally tell me it's dead. That's a bit of a poser. I'd say though, that since it boots (and runs successfully) on the OEM ram, it's probably not related to the slots.

02-19-2012, 02:50 PM

Hello Jeremy. Did you ever solve the problem of your iMac locking up on you? Mine is doing the same thing and I was thinking RAM cards too, but mine are new. I am running OS 10.5.8 on an iMac 2.4 Core 2 Duo 4 gb at 800mhz. It matters not what I am running when the lock up occures. It's even done it while setting on the screen saver. No other warning boxes or chimes occur after the lock up, just a frozen screen with no mouse input capabilities. By the way, there are no start-up chime/bong when you start the machine either. Thought I'd through that in as an additional clue, whether that is helpful or not, I don't know.

02-19-2012, 08:20 PM

Originally Posted by Sid Coleman

Hello Jeremy. Did you ever solve the problem of your iMac locking up on you? Mine is doing the same thing and I was thinking RAM cards too, but mine are new. I am running OS 10.5.8 on an iMac 2.4 Core 2 Duo 4 gb at 800mhz. It matters not what I am running when the lock up occures. It's even done it while setting on the screen saver. No other warning boxes or chimes occur after the lock up, just a frozen screen with no mouse input capabilities. By the way, there are no start-up chime/bong when you start the machine either. Thought I'd through that in as an additional clue, whether that is helpful or not, I don't know.

Yes, I did fix it. I returned yet another package of ram and then all worked like a charm, not a single lockup since then. It was, however, a mac mini not an iMac, but I'd assume both could have the exact same type of problem.

Jeremy