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HelpMePls

macrumors member
Original poster
Apr 19, 2019
32
1
Hello I have a 27” Late 2015 iMac that won’t install any OS on the internal drive.

It loads fine with an external hard drive.

When I try to install an OS on the internal drive it goes into a boot loop of restarting over and over.

Any idea why?

I’m also asking that the people that responding on here either know the fix themselves or knows of a fix to this issue. I hate people guessing and asking a stupid amount of questions and totally wasting my time.

Thanks
 

Fishrrman

macrumors Penryn
Feb 20, 2009
29,223
13,293
"I’m also asking that the people that responding on here either know the fix themselves or knows of a fix to this issue. I hate people guessing and asking a stupid amount of questions and totally wasting my time."

With an attitude like that, don't expect much help.
We can't see your Mac and as such the only info we have to go on is what you tell us, and even then we have to "guess".

If you want "certainty", take it to a repair shop.

OK, the rant is over.
Now...

You haven't told us WHAT KIND OF DRIVE is inside the iMac?
Is it a fusion drive?
Is it a platter-based HDD?
Is it an SSD?

When you boot the computer externally, does the internal drive mount on the desktop?

Can you go to disk utility?
Then, run the "repair disk" feature on the internal drive.
What kind of report do you get?

What is on the internal drive now?
Are there files on it you can access?
Do you want to save them?
Can you copy them OFF OF the internal drive to another drive?

If so, I would:
- Back up the stuff I want to save on the internal drive
- Erase the internal drive (what format you erase to depends on what OS you want to install)
- Try reinstalling the OS (unless you're in the "boot loop" again.

There are "other ways" to get a copy of the OS onto the drive.
One way I would recommend:
- download CarbonCopyCloner (free to download and use for 30 days)
- use CCC to clone the OS (and other stuff) from the external SSD to the internal drive
- see if it will boot that way (if it doesn't, just erase it and try something else)
 

HelpMePls

macrumors member
Original poster
Apr 19, 2019
32
1
Fixed it myself guys.

It was simply a case of corrupted ram.

I googled an article which had the exact same symptoms as my iMac - only my iMac would load an OS with an external drive whereas his wouldn’t.

I’ll leave this post up on here if it helps anyone else out!

P.s. could you imagine if I took the time to write back to every one of Fishrrman’s questions and “trailed and errored” every one of his “assumed fixes”? I would’ve wasted even more precious time of my life. I had done that in the past and wasted a few minutes with all his guesswork and it simply got me nowhere... *rant over* haha, glad I figured this one out on my own before reading his comment.

TLDR Answer: I swapped the Ram (which must have gotten corrupted) and problem fixed!!!
 
Last edited:

Fishrrman

macrumors Penryn
Feb 20, 2009
29,223
13,293
"Fixed it myself guys.
It was simply a case of corrupted ram.
I googled an article which had the exact same symptoms as my iMac - only my iMac would load an OS with an external drive whereas his wouldn’t."

Sounds like a "good solve".
Apple is making things like this more and more picky and difficult.
I'm wondering what was "different" between the factory RAM and the RAM you had in it, that tripped up the OS installer...
 
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