27" Late 2015 iMac and 24GB Ram Problem.

mikeleethomas

macrumors newbie
Original poster
May 17, 2016
10
1
Hi everyone.

I purchased and additional 16GB or ram (2x8) from Crucial to install next to the stock 8Gb (2x4) but the machine won't boot up and I get that dreaded 'tone'.

Is it simply not possibly to install 24GB as every stick has to match?

Many thanks.

Mike
 

scogan

macrumors newbie
May 17, 2016
1
0
Hi everyone.

I purchased and additional 16GB or ram (2x8) from Crucial to install next to the stock 8Gb (2x4) but the machine won't boot up and I get that dreaded 'tone'.

Is it simply not possibly to install 24GB as every stick has to match?

Many thanks.

Mike
I did the same thing, mine worked fine.
 

mikeleethomas

macrumors newbie
Original poster
May 17, 2016
10
1
So weird. I looked in 'about this Mac' and it stated I only had one slot in use despite two sticks being in the machine. So I opened it up and stuck them back in and all of a sudden the fans on my iMac are going through the roof.

Take the crucial ram out, put the Apple stock Ram back in and it won't boot. Stuff is spinning up but the screen won't come on and there's no boot sound.

Was fine up until me inspecting. Any thoughts? :/
 

DeltaMac

macrumors G4
Jul 30, 2003
10,585
2,836
Delaware
Do both an SMC and a PRAM reset.
Another possible way to test is one stick at a time.
(You do not have to install in matched pairs, a single stick will also work for testing :D )

But, if you are positive that you got the correct spec memory from Crucial, it's pretty likely that you just don't have all the sticks properly seated. It takes a firm push until you hear the stick "click" in to place.
 

mikeleethomas

macrumors newbie
Original poster
May 17, 2016
10
1
So turns out the left hand side of the top bay won't fully be pushed. But when I check the stock ram and crucial ram it's not normal that the edges are burnt right?!?!
 

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DeltaMac

macrumors G4
Jul 30, 2003
10,585
2,836
Delaware
Definitely.
Take your iMac in for service. It's likely that your iMac RAM slot is now damaged.

That might happen if the RAM stick was not seated correctly, then you tried to boot with the stick "almost" seated.
Just a small burn mark there, but may have damaged it enough so you can't boot until it is repaired.
 

mikeleethomas

macrumors newbie
Original poster
May 17, 2016
10
1
It's not just that one stick, it's 3 of the 4. Like I say the only reason I noticed was because I only had two installed and when checking my iMac version noticed one wasn't recognised.

Seriously, I love apple but I've never had as many problems as I have done in the last few years with their products.
 

DeltaMac

macrumors G4
Jul 30, 2003
10,585
2,836
Delaware
If the burn spot resulted from a mis-seated stick, and you got flash damage at boot, then you may have blown out the memory controller, or at least the slot interconnect. Anyway, you probably need to have the logic board replaced (unless you are very lucky... )
 
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