Help! Cannot get iMac 12,1 to boot to ANYTHING

jimbob200521

macrumors newbie
Original poster
Jan 19, 2016
26
4
So I picked up an iMac 12,1 yesterday for a song and dance that was said to have a bad hard drive as diagnosed by Apple tech support and a local computer shop. Ok, replace the drive and good to go, right? So far, so wrong. Nothing I have tried has allowed me to get an OS installed or running on this thing. When I got home with it, I removed the glass and started lifting the screen to find that the hard drive was missing (no big deal, I suppose). Long story short, I got the new SSD installed and reconnected a ribbon cable that the previous tech much have not reconnected.

So my journey starts...I will list what I've tried as a list to make this as quick as possible:

-reset PRAM
-Tried installing various OS's from 10.6-10.13. All have various different stages of failure. For example, 10.8 gives me a blue screen with black lines while most others will get to about 3/4 to 2/3 of the boot progress bar then go to a white screen, reboot, then repeat.
-Tried cloning the boot drive of my Macbook running High Sierra to an external hard drive then booting off that. Same thing, gets about 2/3 - 3/4 of the boot bar then repeat.
-Tried booting into the "online" software restore (whatever it's called) failed out and gives me a white screen until I hard turn it off
-Booted into hardware testing and tested: no errors found (didn't do extended test...yet

Any help or suggestions anyone can offer would be greatly appreciated!
 

jimbob200521

macrumors newbie
Original poster
Jan 19, 2016
26
4
Maybe it was not worth the song and dance. Often computers sold without hard drives are suitable only for parts.
I'm still in the camp that it's some odd hardware/software thing that I haven't pinned down yet. It'll run the Apple Hardware Test all the live long day (currently finally running the extended test with the additional memory I added removed). I just don't want to give up on this thing as an i5 iMac system would be useful to have around the house.
 
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jimbob200521

macrumors newbie
Original poster
Jan 19, 2016
26
4
How did the all day hardware test go? Have you tried simply replacing the hard drive cable?
Thank you you for replying! The extended hardware test revealed no errors found. I've also tried booting both from an internal SSD as well as an external USB enclosure, neither successful. I've also used various USB drives as installers, no go there, either :(
 
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gauchomac

macrumors newbie
Jan 14, 2019
11
5
Florida
I picked up a 12,2 27" with a similar issue. I haven't pulled the screen to check the hard drive, but there must be one as the ASD checked the SMART status. A guy loaded WIN10 on it, and apparently the OS partition is gone. I have tried Internet Recovery (white screen @ 50%), Booting an installer USB with High Sierra on it (white screen @ 70%). I can run the ASD EFI boot tests, but again the white screen if I try to boot the ASD OS tests. I have reset the RAM, SMC, etc etc. I know these macs had a possible issue with graphics cards; I don't have any glitching at all, but it seems to me the white screen is at the point it changes graphics modes during the install/boot. The machine loads Apple Diagnostics, and it passes every test. I checked memory with both Apple Diagnostics and the EFI ASD. Really be a shame to just part the thing out, but that may be where I'm headed.
 

Zdigital2015

macrumors 68020
Jul 14, 2015
2,402
2,799
East Coast, United States
So I picked up an iMac 12,1 yesterday for a song and dance that was said to have a bad hard drive as diagnosed by Apple tech support and a local computer shop. Ok, replace the drive and good to go, right? So far, so wrong. Nothing I have tried has allowed me to get an OS installed or running on this thing. When I got home with it, I removed the glass and started lifting the screen to find that the hard drive was missing (no big deal, I suppose). Long story short, I got the new SSD installed and reconnected a ribbon cable that the previous tech much have not reconnected.

So my journey starts...I will list what I've tried as a list to make this as quick as possible:

-reset PRAM
-Tried installing various OS's from 10.6-10.13. All have various different stages of failure. For example, 10.8 gives me a blue screen with black lines while most others will get to about 3/4 to 2/3 of the boot progress bar then go to a white screen, reboot, then repeat.
-Tried cloning the boot drive of my Macbook running High Sierra to an external hard drive then booting off that. Same thing, gets about 2/3 - 3/4 of the boot bar then repeat.
-Tried booting into the "online" software restore (whatever it's called) failed out and gives me a white screen until I hard turn it off
-Booted into hardware testing and tested: no errors found (didn't do extended test...yet

Any help or suggestions anyone can offer would be greatly appreciated!
If I may offer some suggestions.

Do you have a 10.6.8 DVD ROM? If so, try to boot from that holding down the C key on the keyboard. Also, make sure to use a wired keyboard, Apple if you have one.

Apple does still sell the Snow Leopard DVD-ROM here - https://www.apple.com/shop/product/...dda72b28dd8116e34dd4dd78c33d20e19c0f280a0a4ee - but I am not sure if that is worth the cost at this time.

Pull all the DRAM and see if you can find either Samsung or SKHynix branded DRAM, if so, only put those back into the machine. If it shows third party branding, simply keep them out. If you have questionable DRAM, install just one of them into of the top memory slots (the top slot when the iMac is face down). I do not think it matters which one.

Find a known good ethernet cable and attach it to your router and the iMac, see if it will pick up a DHCP address and show up in your router's web admin. Try running the Network Restore again if it does.

Boot up the iMac, hold down the Option key and see if you can actually choose the internal hard drive for boot.

Get a set of suction cups and pull off the front glass, carefully remove the display ( you will find tutorials on iFixit, MacSales, etc. and go through all the wires and such to make sure they all got plugged back in, no frayed wires, no exposed wires touching metal, etc. It's possible some tech pulled it apart and did not put it back together correctly or failed to reseat something properly or simply pinched a wire.

Good luck!
 

KonaBlend

macrumors member
Oct 18, 2008
32
4
So I picked up an iMac 12,1 yesterday for a song and dance
getting that far into boot/install process smells like a memory hardware issue.

try (if possible) isolating the memory sticks. if you have 4 ram sticks, run with 2. find out the minimum 2 it can run with (I'm assuming it can run with 2). if it still fails, replace those 2 with the untested 2. also give a visual on mem sticks, are they same type/brand? usually at a minimum pairs have to exactly match. also is memory speed correct for system? should be 1333MHz PC3-10600 DDR3. also you mentioned having "added" RAM, maybe try just with only those memory sticks.

also; long shot, check the video card. Imac 12,1 are the last models that have discrete graphics (via MMX) so an experimenting upgrader may have left it with an incompatible card. It should be an AMD Radeon HD 6750M or 6770M, with 512MB VRAM. if I read everymac correct, there was an EDU 12,1 with only 256MB VRAM (maybe only 2 SDRAM chips instead of four) like shown in this teardown photo... - i'd suspect EDU version is pretty low on the compatibility ladder of things.

 

gauchomac

macrumors newbie
Jan 14, 2019
11
5
Florida
To follow up on my post above, the 2011 27" iMac I got had the 6790 board, and would try to boot and fail at above 50% on everything - Internet Recovery, or a USB. It would look fine, and then go to gray screen (and freeze). I was able to load an ASD disk, EFI only, and it found no fault with the logic board or GPU or HDD. Given the GPU issues with the 2011, I went ahead and bought a GTX 675 (Alienware), and used another mac to install High Sierra on the HDD (a Windows only tech had installed Windows10 on the main partition). Put it back together, and it booted with zero issues.

jimbob200521, this sounds a lot like your issue. The way I looked at it, if the new gpu board didn't work, I could recoup at least 75% of the price reselling it on eBay, so it was a reasonable gamble. I'm not excited about ever removing that logic board again, though.
 
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jimbob200521

macrumors newbie
Original poster
Jan 19, 2016
26
4
Sorry for the lack of responses guys, I haven't had much time to play with this thing since I got it. I have taken the information given and did some looking. Would what is linked below be a viable option if my issue is indeed a video card problem? Seems like $50 for a replacement video card wouldn't be a bad option...

https://eshop.macsales.com/item/Apple/6615994/
 

jimbob200521

macrumors newbie
Original poster
Jan 19, 2016
26
4
Starting to go a bit beyond that song and dance business.
That's half the fun, though. I've been mainly into PC's over the years, and Mac's when circumstances would allow, and I've enjoyed near every project I've gotten my mits on. Some work out and some don't but I always learn something, enjoy the troubleshooting, and seldom regret a purchase/project. While it would have been nice to get this and have it work straight away, that doesn't mean I'm upset that I am having to do some troubleshooting and work on it. Worst case, I don't spend any more money on it and it becomes a nice looking piece on my Mac shelf. Best case, I buy a video card or whatever I end up needing and have a good iMac to use. Either way, I'm good with the outcome.
 

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