Model A1225 / Early 2009 / 2.66, 2.93, or 3.06 GHz Core 2 Duo processor

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Won’t boot from new SSD

I have a 24” 2009 iMac that I’m trying to replace the original HDD with a Western Digital Blue 250GB SSD.

With the SSD in an external case the iMac sees it just fine and I was able to install OS 10.11 on it and even boot from it that way.

When I install it in the iMac it won’t boot from it at all. I just get a white screen with no flashing question mark??

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After further research and tinkering it turns out I needed a new Sata data cable. Apparently it provided good enough signal to work with the slower data rates of a hdd but not a new SSD. Hence the red cable.

I will do a better job of rerouting and installing when I’m ready to reassemble but yeah, new cable...

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i can't thank you enough right now.

you have saved my past 2 days of troubleshooting by using a standard sata cable as a tryout and replacement.

i just did the same as you did and it works like a charm.

(sandisk ultra ii 240gb)


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Bet you didn't remember to format it GUID Mac OS X Extended before you put a system on it. The Mac doesn't how it's formatted externally. It does care when it's internal.. Remember to address the thermal sensor issue with one from OWC if you haven't. Run away fans may ensue if you don't.

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I did format as GUID Mac OS X Extended.


Glad you solved your problem. Come back if the fan starts bothering you. Would you mind telling others exactly where you got this cable and what it was.


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i had the same problem and abrixen's fix worked for me too:

solved problem:

24" imac 9,1 won't boot from any ssd if connected to the hdd bay cable


the screen stays white if the ssd is connected to the main sata port, where the hdd used to be.

no apple logo, no question mark at boot.

no option boot menu possible even if another bootable drive is connected to usb.

no option boot menu even if a bootable cd or dvd is inserted


just like @abrixen i took a standard red pc sata cable with a short straight plug on both sides, to be sure the bezel will close if it is plugged to the mainboard

reason for a short straight plug instead of an angled sata cable was, that any angled sata cable i could find had the angle pointing in the opposite direction, so if connected to the board it would point towards the wifi module

(a supermicro sata server cable was the one with the shortest straight plug i could find. almost as flat as the angled plugs as you can see comparing the original sata power cable to the supermicro sata data cable in the picture below)

to save time i didn't bother to route the sata cable below the main board, as it was so thin, that it fittet between the cooler brackets and the display and the temperature seemed to be the same to less compared to the heatsink side below the board, so if it is routed as on the picture the imac display will fit cleanly with no more pressure from below as the pressure the sponge spacers apply without an additional sata cable.

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@abrixen: many thanks for sharing your fix with a picture.

without your pic i wouldn't even have tried using a standard sata cable because i'd not even have expected the connectors to be standard sata on BOTH sides.

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abrixen will be eternally grateful.
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