Screen stays black on startup

[kwillems]

I've got an iMac 27 2017 with an i7, the 580 graphics card and an SSD of 1 TB. I've extended the RAM to 40 GB.
Everything worked fine, but the last couple of days the screen stays black on startup every once in a while. The fan is running and the screen get's black-grey (as it is 'on'), but than nothing happens.
After putting the iMac off and on again everything works fine.
I've already did reset NVRAM and SMC. Starting the machine while pushing D results in no errors.

What can this be?

 

[DeltaMac]

The RAM can be the problem, I think. If it is slightly out of spec, you can have weird things that can happen during boot, but generally, you have errors of some kind, and maybe the occasional kernel panic.
What brand of RAM did you add to your iMac?

 

[kwillems]

The RAM can be the problem, I think. If it is slightly out of spec, you can have weird things that can happen during boot, but generally, you have errors of some kind, and maybe the occasional kernel panic.
What brand of RAM did you add to your iMac?

I've used Crucial memory. I've noticed no problem with it so far

 

[DeltaMac]

Do you usually shut your iMac off? or usually sleeping?

 

[kwillems]

Do you usually shut your iMac off? or usually sleeping?

I'm used to shut the iMac off; I guess that's a bad habit.
[doublepost=1522603750][/doublepost]Well, I'm going to reinstall the OS right now. Let's see what it will bring.

 

[nambuccaheadsau]

If it is still under the 12 months warranty do not muck about. Take it back even if it is a terrible job hulking it about.

 

[Papanate]

Before you bring it in - have you started it in 'Safe' mode?

Also call Apple Support and see if they have a Fix or a bulletin
about this behavior.

Then if those don't work as @nambuccaheadsau just noted - if it's
still under warranty (Apple Care or basic) bring it in immediately.

 

[kwillems]

Before you bring it in - have you started it in 'Safe' mode?

Also call Apple Support and see if they have a Fix or a bulletin
about this behavior.

Then if those don't work as @nambuccaheadsau just noted - if it's
still under warranty (Apple Care or basic) bring it in immediately.

I've reinstalled macOS, but the issue unfortunatly still occurs.
I will contact Apple Support. My iMac is still under warranty. As far as I know their office will be closed tomorrow in my country, so i'll call them tuesday.
Meanwhile, if anyone can explain this or has any suggestion, please let me know.

 

[jgelin]

The RAM install guide from Apple says this is a possible behavior when first installing ram and it is initializing. Have you tried to reset the SMC to see if this fixes after the next boot up after?

 

[kwillems]

The RAM install guide from Apple says this is a possible behavior when first installing ram and it is initializing. Have you tried to reset the SMC to see if this fixes after the next boot up after?

The RAM was installed in October when I bought the iMac. I had no problems until two days ago. I did already reset NVRAM en SMC with no result.

 

[Papanate]

The RAM install guide from Apple says this is a possible behavior when first installing ram and it is initializing. Have you tried to reset the SMC to see if this fixes after the next boot up after?

He said he did the two common resets.

[doublepost=1522637603][/doublepost]

I've reinstalled macOS, but the issue unfortunatly still occurs.
I will contact Apple Support. My iMac is still under warranty. As far as I know their office will be closed tomorrow in my country, so i'll call them tuesday.
Meanwhile, if anyone can explain this or has any suggestion, please let me know.

Did you boot to safe mode?

 

[kwillems]

He said he did the two common resets.

[doublepost=1522637603][/doublepost]

Did you boot to safe mode?

Sorry, forgot to mention. Yes, I did boot in safe mode. It gave no relevant information (as far as I can see) nor did it solve the problemen.

 

[kwillems]

He said he did the two common resets.
[doublepost=1522637603][/doublepost]

Did you boot to safe mode?

I spoke with Apple Support; they appeared to be working today. They've asked me to bring the iMac in.

But I did some further testing. That's in fact a matter of patience, because the issue occurs say once every ten times. The testing brings up two more questions:

• Could this be caused by my HP Laserjet Pro CM1415fn printer?; It's connected with my iMac via USB
• Also I noticed directly after booting the fan is speeding up to something like 1450 - 1480 rpm during 1.5 seconds. Is that normal behaviour?

[EDIT]
Forget my printer; after some tests the issue also occurs with the printer disconnected.
[/EDIT]

 

[Papanate]

But I did some further testing.

You could try one more thing. Take the Ram out - and then put a single stick in and boot.
If it doesn't do the black screen after repeated boots - put the other stick(s) in one by one.

Now that said - Since Apple says take it in - I would rather than waste my time solving their
issue.

 

[Fishrrman]

1. Take the self-installed RAM -OUT-. Restore it to factory configuration.
2. Run like this for 2 days. Does anything change?

 

[kwillems]

1. Take the self-installed RAM -OUT-. Restore it to factory configuration.
2. Run like this for 2 days. Does anything change?

I already removed the Crucial ram, but the issue still occurred (after 10 reboots).

BTW: why two days?