iMac Intel 27". EMC 2309 (Late 2009, Core 2 Duo 3.06 or 3.33 GHz), EMC 2374 (Late 2009, Core i5 2.66 GHz or Core i7 2.8 GHz)

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Beeps on startup, but RAM known to be good

Last winter this iMac was dropped and the logic board was damaged, I changed it and it worked.

Early on I replaced the HD with a 3TB one (so had to install HDD Fan Control) and the optical drive with an SSD.

In the very beginning, before closing it up after the logic board replacement, I noticed problems with the graphics card, it would show artifacts then freeze rather quickly, but tests showed one of the fans was not spinning right, so I changed it and it worked perfectly for about 10 months. No problems whatsoever.

Then, recently, 2 or 3 times the screen showed artifacts and froze, though the last time was about a month ago.

What is also happening consistently is that it won't start up the first time, I get the single chime (no RAM I believe), or sometimes, 1 out of 10, I get the triple chime (bad RAM). In the beginning it would start after 2-3 tries, then work fine, sleeping and waking up without a problem.

Now, for the last couple weeks, it takes like sometimes like 10-15 tries to get it to start up, working fine, but then it will rarely wake up after going to sleep. I have to turn it off then turn it on again. Of course I've tried several different kinds of RAM in all different positions, to eliminate that as a a possibility. I am now using 100% known good RAM modules from other Macs.

So of course it seems I could set it to never sleep, but for fairly obvious reasons I don't want to do that.

Any ideas???

Could the graphics card could be causing the startup problems? I actually have another card I can try right now but I'd like to get an opinion before opening it up again and tinkering. It's not a fun computer to open. And oddly enough yesterday my SSD failed completely, so I put in a new one. The problem seemed to have disappeared, but then it returned.

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You have quite a history here! I think you have a few issues here.

First I think your over heating your system: FanControl is not the best answer while it does work it also creates issues. People discovered they could use the same manufactures HD as their current HD OWC Blog on Late '09 systems. Which I recommend first. I've heard a spare optical drive sensor could be used if you splice it in and mount it to the HD case (I've not tried this my self).

Have you been logging what your temperture and fans condition your monitoring software is reporting? I like Temperature Gauge but others will also work. You should note if the temp of the GPU is getting to high.

Have you cleaned the dust build up on the fans and the heat exchanger fins? As well as the logic board. You may want to start there.

Beeping: What is the beep code? Review these TN's Intel-based Mac Power On Self Test RAM error codes & Mac computers: About startup tones. While your EFI may need to be upgraded I would hold off on that for now until your system is stable. Please tell us what the code is.

As to having problems starting up: I would disconnect as much of the USB and/or FireWire external hardware and see how the system reacts. If you do find it improved things slowly add in the devices. You also may want to use powered USB hubs if you don't now.

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My heat seems to be fine, I've also tried now disabling the SMART reading (and so the hard drive fans is at high RPM constantly, keeping it especially cool). All the temperatures are pretty low, especially as its cold in my apartment now, and besides, the problem didn't occur when it was warmer.

90% of the time I get 1 beep (no RAM) and once in a while I get three (doesn't pass check). But I've tried all combinations of slots and chips, I think that is completely ruled out, unless somehow the logic board is not accessing the RAM correctly.

I've also tried starting with and without any cables connected, doesn't change anything.

Oddly, once in a while it starts up and it cannot access my Apple keyboard/mouse, until I disconnect it then reconnect it. I thought the new keyboard I bought from Apple was defective, so I returned it, but the same problem occurs sometimes.

My question remains whether a faulty graphics card could possibly cause these symptoms... or I guess the culprit would be the logic board.

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I think it's worth repeating that the computer works absolutely perfectly while it's on. No flaws whatsoever. Just 1) Doesn't always pass power on checks (from off and from sleep) 2) Sometimes turns on without access to keyboard (haven't checked if it is that none of the USB ports work)

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With the new info, I'll say your logic board has cold solder joints on the controller chip. If your system is not running hot as you claim (there is not buildup of dust on the logic board or fans) The beep code implies bad memory but in this case the logic downstream is having issues if you have tried other modules and given the other symptoms with starting up I think thats the only likelihood. No, the GPU wouldn't cause these type of issues, unless you are using the wrong memory modules. But, then it would be the modules not the GPU that still needs to be fixed.

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OK, I'm pretty upset. I replaced the motherboard (and case, which was pretty twisted, figured it could have damaged the board somehow) and I still have the problem. What else can cause beeping??? This is so so strange. I've tried so much RAM, known good as well.

Does anyone know what other component could cause this problem?

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So if anyone is following this still, I tried replacing the graphics card (had an extra one around) and tried booting having components disconnected, one by one (airport card, bluetooth, sd card, etc etc.) and nothing worked. Practically all of the sensors were replaced with the new chassis (except a couple, such as the optical drive).

I'm thinking that practically the only thing that remains is the processor itself.

Or can anyone else chime in as to what else could cause these beeps?

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I personally believe that your problem is with your power supply. Being that its some time after you posted this problem I doubt that we will ever truly find out what it was that corrected this issue.

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Apple seems to only have a couple of different beep codes. I seem to be getting the same 3 beep code and the single beep code. I recently removed the logic board from my iMac (2013 slim model) to install a wall mount. When i put everything back together it booted up without pressing the power button and immediately beeped 3 times. So i began the lengthy process of swapping memory modules in and out of each slot, trying one at a time, so on and so forth. Sometimes when no RAM is installed, I still get the 3 beep code. I can't seem to figure out what else might be wrong, or if it has something to do with the iMac turning on by itself? There are what look to be 4 LEDs on the logic board, 2 light up green when it comes on and only one when its powers off but still plugged in (not sure if that is an indication of anything or not). At any rate, Im starting to wonder if there are two spots I can bridge together in an effort to try and clear the code or something. I'm just a little frustrated, mainly because I dropped the %#*@ screen when I was trying to put it back together.. Thanks in advance for any help you might be able to offer

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spacec0w will be eternally grateful.
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