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Model A1312 / Mid 2010 / 3.2 GHz Core i3 or 2.8 & 3.6 GHz Core i5 or 2.93 GHz Core i7, ID iMac11,3

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iMac stuck on white screen after changing ram

I recently upgraded the RAM in my mid 2010 27” iMac and now it just boots to a blank white screen.

I’ve tried everything multiple times. Resetting the SMC, NVRAM, booting into recovery, booting off an external drive. Putting the original RAM back in it. Then trying all the above all over again.

All I get is a white black screen!. No apple logo, nothing! It won’t even load boot options when I hold down the option key.

The iMac was working perfectly until today. Does anybody have any clue what could be the problem?

I’ve searched the forums here, tried every solution, googled my issue and even went through the YouTube tutorials but every tutorial assumes that the iMac should at least show the Apple logo when trying to boot up, or at least that it will give me a boot selection screen when holding down option on startup.

I’m very familiar with all of those tricks because this isn’t the first time I’ve had a Mac with a similar issue but it is the first time that I literally get nothing whatsoever but a blank, bright white screen.

My thought was that it could be a graphics card issue but this iMac has never shown signs of a graphics issue and the only thing that coincides with the issue is a routine RAM upgrade that I’ve performed many times over the years on every Mac I’ve owned.

Could it be possible that something could have suddenly happened with the video card at the same exact time I upgraded the RAM?

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Are you sure you got the RAM fully seated and using proper antistatic precautions?

What does the onboard diagnostic LED’s telling you?

Locate the black covered taped area in the bottom left corner

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Here's a breakdown of the onboard diagnostic LED's meaning:

LED 1 - Indicates that the trickle voltage from the power supply is detected by the main logic board. This LED will remain ON while the iMac is connected to the AC power. The LED will remain on even when the computer has been shut down or put to sleep. The LED will turn off only if the AC power is disconnected or the power supply is faulty.

LED 2 - Indicates that the main logic board has detected proper power from the power supply when the computer is turned on. This LED will be ON when the computer is turned on and the power supply is working correctly.

LED 3 - Indicates that the computer and the video card are communicating. This LED will be ON when the computer is communicating properly with the video card. If LEDs 1 and 2 are ON and you heard the startup sound, but LED 3 is OFF, then the video card might be installed incorrectly or need replacement.

LED 4 - Indicates that the computer and the LCD display panel are communicating. This LED will be ON when the computer is turned on and video signal is being generated. If the LED is ON and there is no image on the LCD display panel, the LCD display panel or inverter might be installed incorrectly or need replacement.

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Thank you for your help.

Yes, I always make sure to ground myself and work in a static free area before working with the innards of the iMac, and the RAM is snapped all the way in and the computer can detect the RAM. Putting the original RAM back in it and letting it sit overnight, the problem seemed to fix itself only for a new problem to pop up.

The iMac boots to the desktop and basically "works" just fine now. That is, for a few minutes, and then the display (not the computer, just the display) turns itself off, while my programs and the OS continue running. I can see that it works fine when I use remote VNC screen sharing to log into it from my MacBook Pro.

I tried the flashlight trick to see if it's just the backlight. But it's not just the backlight. It's the entire screen. Also, the screen turns itself back on and works wonderfully if I use it as a second display for my MacBook Pro via Target Display Mode.

But when I try to use the iMac as is, without the MacBook Pro attached, it sporadically goes black. I'm truly confused because if it works perfectly as an external display for my MacBook Pro, then that's should mean that there is no issue with the display. Right?

I thought it may be a software issue in macOS so I booted into the boot camp partition on the iMac and I still get the random black screen. The only thing I can think of at this point is that it might think (on a hardware level) that it's in Target Display Mode when nothing is connected to its display port.

I’m not as bothered by this issue as I was with the white screen issue because it at least serves a purpose as a large monitor for my laptop. But it would be nice to have it fully functional system again!

By the way, is it safe to power on the iMac with the display removed so I can take a look at the diagnostic LEDs on the board?

par

This is starting to sound like the thermal sensor on the display is failing or firing off due to a over temp.

Lets get a better idea on the temps, install this great app! TG Pro the free version is all we need, but I'm sure you'll grab the full version as its such a useful tool! Any ways... take a snapshot of the sensors, make sure you get them all you may need to adjust the window size the get them in one snapshot. Post it here for us to see Ajout d'images à une question existante

As far as the onboard LED's you can run the system with the display disconnected. but given the issue we now have we need it connected. FYI of course the last two LED's won't light as they are dependent on the display.

par

Thanks! I have added a screenshot TG Pro sensor readings after leaving my iMac on for a couple hours. It is attached to my original post.

par

I don't see anything standing out.

Let's give this a try plug in an external monitor. Does it still show your desktop when the internal goes white?

par

The white screen problem actually went away. Now the display just intermittently goes black.

When I connect another monitor, and also when I use the iMac as a display for my MacBook, the iMac display works fine.

But when no other monitor or computer is connected to the iMac, the screen refuses to stay powered on for more than a couple minutes.

Today, I set the lower left corner of the display as a hot corner that puts the display to sleep. So now, when the screen goes black, I (blindly) move the cursor to that corner and then press a key to "wake" the display back up, which works until the display turns itself off again.

It is truly a confusing problem because the iMac doesn't seem to be "aware" that anything is wrong. The only thing I can think of that could be remotely plausible as the cause is that maybe the inverter is going bad and the iMac just isn't detecting it. But if that were the case, I don't know why the iMac display works when I have a second screen connected to it.

par

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Jared S (jscorpio87) sera éternellement reconnaissant.
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