iMac won't boot - white screen of death

[Fried Chicken]

I've seen so many posts, now it's my turn: HELP!

My iMac won't boot. I was having period issues over the past 2 weeks where the computer would hang during startup. Now I just get the white screen of death.

Hardware:
2012 iMac, i5, GTX 680mx 2GB, 16GB RAM
2GB HDD + 1TB SSD partitioned into two 500GB partitions yielding:
2.5TB fusion drive (HFS) + 500GB Windows partition.
High Sierra

Symptoms:
I had some issues where Windows would freeze completely requiring a hard restart, however restarting into MacOS was never an issue, although sometimes it would restart twice. I've been playing some intense games in Windows recently (X-Plane).

Then today I had that same issue (no games running). I tried a reboot into MacOS, no problem, but when I tried to restart I started having serious issues. At first it would boot to the apple logo then get stuck. I tried resetting the NVRAM (cmd + opt + P + R). The SMC reset (unplug 15 seconds). Those didn't work. Safe boot worked once, but when I tried a normal restart it didn't work.

Current state:
Starting the iMac gives a white screen and that's it. It doesn't give me the option for boot camp. I do hear the HDD doing stuff, though no signs of failure.

Unfortunately I don't have a recovery partition, and I'm making a bootable high Sierra install now. Fortunately I have good backups, although not everything is included in my time machine, so I want to avoid that route if possible.

I'm going to let the Mac sit with the white screen for a while to see if it can sort itself out. Does anyone have any ideas?

Not getting to the boot manager is already weird. Any help is much appreciated!

Thanks

 

[redheeler]

Is the Windows partition on the HDD or SSD portion? HDD failure is one possible explanation given the symptoms you described.

Will the iMac boot into Recovery? If so, run First Aid on the drives using Disk Utility.

 

[Juicy Box]

My Late 2012 27" iMac with the original 1TB Fusion Drive had a very similar issue.

It s a long story, but it began with hanging boots, the OS behaving strangely, and eventually the white screen.

Sometimes I could boot into recovery mode, and a wipe and reinstall would fix the issue...

But it would always come back.

I have seen issues similar in the past with failing hard drives, and that was what I suspected.

I had Apple Care, and I would end up making multiple phone calls to support, which would lead to multiple Apple Store visits, where the iMac would always pass their HW diagnostic test.

They would say that the OS somehow got corrupted, do a wipe, and the computer ran great from a short period of time, then I would start the Apple Support process all over again.

I told them that I was pretty sure it was the Fusion Drive, but they said that there was doing they could do since it kept passing their HW test.

They even kept the iMac for a week to do a extended HW test, which it still passed.

12 days before the end of my warranty, the iMac's Fusion Drive total broke. I couldn't get it to boot into recovery, nor and external boot drive. Just a white screen.

I did the Apple Support process for the last time, which at the Apple Store, they couldn't even get their HW test to boot for over two hours. When they did, the drive did not pass the test, so Apple replaced it.

Maybe this is your issue.

 

[Fried Chicken]

I just dropped it off at the Apple Store after speaking with applecare.
The Genius suspects it's exactly that; the fusion drive got messed up somehow and this causes the boot loader to act up.

If this is the case, I hope they can at least get it to a running state. I was planning on ditching the fusion drive anyway whenever BF comes around and I can get a 2TB SSD.

Windows is on the SSD partition for fast gaming.

 

[Juicy Box]

I just dropped it off at the Apple Store after speaking with applecare.
The Genius suspects it's exactly that; the fusion drive got messed up somehow and this causes the boot loader to act up.

If this is the case, I hope they can at least get it to a running state. I was planning on ditching the fusion drive anyway whenever BF comes around and I can get a 2TB SSD.

Windows is on the SSD partition for fast gaming.

In my experience, swapping the drives fixes these issues. Also, wiping the drives might fix it, but if there is a problem with the drives, your issue might come back.

 

[Fried Chicken]

In my experience, swapping the drives fixes these issues. Also, wiping the drives might fix it, but if there is a problem with the drives, your issue might come back.

Unfortunately I have no way to wipe the drives in the first place, because I don't have a recovery partition, I can't boot into internet recovery, I can't boot to an external bootable MacOS disk, I basically can't boot.

Swapping the drives might work, but now it's in the hands of Dennis at the Apple Store. Hopefully he can put two-and-two together.

 

[Juicy Box]

Unfortunately I have no way to wipe the drives in the first place, because I don't have a recovery partition, I can't boot into internet recovery, I can't boot to an external bootable MacOS disk, I basically can't boot.

I understand, this is one reason I was not happy about the Mac Mini having soldered storage.

SSDs are more reliable that HDDs, but they still fail, and many times without warning signs.

Hopefully your issue gets fixed, let us know what they do.

 

[Fried Chicken]

I understand, this is one reason I was not happy about the Mac Mini having soldered storage.

SSDs are more reliable that HDDs, but they still fail, and many times without warning signs.

Hopefully your issue gets fixed, let us know what they do.

Thanks. I have to say, applecare was very generous in offering this free and/or discounted repair on a product that's been out of warranty for 2 years.

 

[Fishrrman]

OP:

Are you saying they're doing the repair for free?
If so, that's great.

By the way...
IF you had a bootable cloned backup created by either CarbonCopyCloner or SuperDuper, getting booted and up-and-running after an internal hard drive failure would have been "child's play".

Both CCC and SD are FREE to download and use for 30 days.
When you get things sorted out, I suggest you give one of them a try.

 

[Fried Chicken]

OP:

Are you saying they're doing the repair for free?
If so, that's great.

By the way...
IF you had a bootable cloned backup created by either CarbonCopyCloner or SuperDuper, getting booted and up-and-running after an internal hard drive failure would have been "child's play".

Both CCC and SD are FREE to download and use for 30 days.
When you get things sorted out, I suggest you give one of them a try.

If only.

The computer wouldn't even recognize a USB installer I created. Just the white screen of death.