21.5 - 27" iMac HD REPLACEMENT

Discussion in 'iMac' started by All Taken, Dec 29, 2009.

  1. All Taken macrumors 6502a

    Dec 28, 2009
    I am due to be upgrading my iMac with a SSD drive in the next couple of days, I have the intel G2 going into the optical bay by means of a optical caddy. I figured whilst I was in the iMac that I could upgrade the Hard Drive to a larger Capacity.

    Many will be saying "Why doesn't he just put the SSD in place of the hard drive and use an external for media?"

    Well... The hard drive slot uses a new sensor that plugs into the hard drive, reading the internal tempreture to adjust fan speed acordingly. If I change the drive the fans will spin at full RPM unless I short the cable (I'm not a fan of shorting cables nor am I a fan of software fan control)

    The model of hard drive in my 21.5" iMac is the Seagate 500GB: ST3500418ASQ

    I have a theory that it can be replaced with this drive (Seagate 1.5TB): ST31500341AS

    Can anyone see where I am going with this? I am wondering if the drive above will have the correct pins for the temp sensor cable - the model numbers seem to match apart from the Q at the end and the 3 digits prior to AS.

    Could anyone else find more info? I am very close to buying the drive and probably will but it would be nice to get some feedback from the community and possibly open up the gates for late 2009 iMac hard drive upgrades without shorting the cable.

    I would also like anyone with a 1TB or 2TB internal Hard Drive to post the info from System Profiler, e.g:

    Capacity: 500.11 GB (500,107,862,016 bytes)
    Model: ST3500418ASQ
    Revision: AP24

    If I am correct the Revision number is the Drive Firmware. If I can get a hold of another drive i.e 1TB or 2TB minus the mysterious "Q" in the model number, then perhaps I could flash the Firmware Apple is using to the new drive (if that is needed, it may be as simple as connecting the sensor to the drive and not installing any new firmware).
    Perhaps we will need to wait for a software update for a firmware image or perhaps it's possible to extract the firmware from a 1TB or 2TB Apple drive.

    Que the community....
  2. spencers macrumors 68020


    Sep 20, 2004
    Call Seagate.
    If you're buying locally, ask the store if you can open the box to check.
  3. tkraatz macrumors newbie

    Jan 3, 2010
    I'm running a Western Digital, but my understanding is that the new iMac models do not have universal manufacturer compatibility. The ST31500341AS is on the Seagate systems upgrade path as listed at Other World Computing

    WDC WD1001FALS-40U9B0:

    Capacity: 1 TB (1,000,204,886,016 bytes)
    Model: WDC WD1001FALS-40U9B0
    Revision: 20.04F20
  4. All Taken thread starter macrumors 6502a

    Dec 28, 2009
    Just incase anyone else has the same question, Yes the Seagate late 09 iMacs can be upgraded with the same product family drives. I had to open my iMac up to do a SSD upgrade and since nobody had a definitive answer to give I found out for myself :rolleyes:

    The Model Number on the drive is a standard Seagate Model Number for the Barracuda series.

    The Temperature sensor connection is also on the same Barracuda family.

    Result: No more shorting the temperature sensor to upgrade the hard drive.
  5. darrellishere macrumors 6502

    Jul 13, 2007
    You can use smc fan control, as a friendly semi permeant solution for reducing or increasing you hd fan-speed, without messing with that new sensor. Best solution for ssd upgrade anyway.

    What still worries me is that opening the imac voids the warranty .
  6. All Taken thread starter macrumors 6502a

    Dec 28, 2009
    SMC fan control is one solution. I would much rather use apples solution though. Opening the iMac does not void the warranty as far as I know. Apple will simply refuse to carry out repairs on any part modified.

    All I did with my SSD upgrade was to keep the superdrive safe and simply place it back inside if it needs repair.
  7. wesleyh macrumors 6502

    Mar 23, 2007
    Would be interested in knowing if replacing the seagate drive by one without apple's firmware on it would decrease the "grumbling" sound (clicking sound) so many here speak of.
  8. Tommy Wasabi macrumors member

    Tommy Wasabi

    Sep 10, 2003
    Any Luck with the SSD on the iMac i7 27" Late 2009?

    Did anyone ever figure out if you can control the fan when you replace the 1TB internal HD with an SSD in the 27" iMac i7 (Late 2009)?
  9. i7QuadCoreMania macrumors 6502

    Nov 10, 2009
    if I recall correctly, it is not a 3 pin connector, its a 2 pin one.

    same connector as the other temp sensors in the iMac, technically, those sensors are interchangeable.

    as you recall there is a temp sensor for the Optical drive, if you can find another one, or get the old "Thermistor" from the 24" series.

    I just used a jumper connector and header from spare PC parts bin when I installed my X25M. Thought about the official sensor route, but it costs around 30-40 bucks and hard to find.

    In my opinion, the sensor isn't necessary for SSD, they don't reach the temperatures of spinning HDDs to make use of that sensor.
  10. Tommy Wasabi macrumors member

    Tommy Wasabi

    Sep 10, 2003

    I'm a bit unclear what you did - did you add an external thermal sensor from an older iMac? Did you add an adaptor- and bypass the sensor all together?

    I guess what I'm asking for is a bit more detail <grin> regarding what you did specifically to address the sensor issue.
  11. i7QuadCoreMania macrumors 6502

    Nov 10, 2009
    I was going to do the sensor route, but after finding out how much it costs, 30 bucks before shipping for that sensor is ridiculous. Though I have read someone did use the sensor from a 24" unit, you still need to tape it or glue it to your new hard drive.

    The 24" iMacs had a little black thermistor with a plastic bracket glued to the hard drive. If you can get a hold of that part, the sensor and plastic bracket you can pretty much use any hard drive in there you want. It the sensor connector will plug into the logicboard on the 21, 27" models.

    What I did was use a jumper (those small plastic jumpers on PC mother boards) the ones they use in place of Dip switches.;) I also had a header, basically looks like 2 Pins open on eachside, connected the jumper to the sensor connector, in essence shorting it, (returns same voltage sent) used some electrical tape, carefully moved the wires out of the way and taped it neatly inside.

    Because I installed an Intel X25M SSD, I felt it wasn't worth my while to track down the oem sensor from a 24", but it is possible to use it and install any brand hard drive in there you want.:D
  12. Tommy Wasabi macrumors member

    Tommy Wasabi

    Sep 10, 2003

    So this is what I ended up doing (and some lessons learned) taking apart the iMac 27" Late 2009.

    1. I purchased some suctions cups from Lowes that are used to hang things in the shower for about $2 each - I used these to take off the glass front panel - very easy.

    2. The Vertical Sync cable is NOT a lift off type of chip - it's a ribbon cable that is INSERTED - just pull it out (carefully) - don't try and pop off the chip head thinking it's actually attached. I didn't see this tidbit anywhere so I thought I'd add it.

    3. I replaced the 1TB drive with a 256GB Torqx M28 SSD (Patriot Memory). I didn't go with the replace the DVD/CD route as I use this drive often. To address storage - I have a 6GB DROBO and a 1TB External that I use for data. Anything that requires FAST access (i.e. Parallels, World of Warcraft, Photoshop) I leave on the SSD. Music and movies can be supported over the FW800 with no problems.

    4. To address the Thermal sensor - I ended up jumping the switch. As stated previously - this is a 6 hole connector. ONLY two of the holes have wires. Make sure you connect the two wires. I used some thicker single stranded wire I had laying around the house and then used some black electrical tape to isolate it. This will keep the wires shorted - giving the thermal sensor a 0V reading - which basically keeps the fan off. I am not worried about any heat the SSD may generate - because it doesn't <grin>.

    5. I purchased the Torqx because it also included a mounting bracket for a 3.5" (the SSD is a 2.5" form factor). If you do this - be aware that the bracket will only attach to TWO of the FOUR connection points. The bracket is too short. This really isn't a big deal as the drive is very light and you won't be moving the 27" around like you would a laptop (I hope). Just make sure you tighten down so it's snug. I then used black electrical tape to "seal" the edges so it may move a bit - but won't be flopping around. The tape holds it well enough that if you ship it - it won't be moving enough to touch anything else. Not the best solution for sure - but good enough for my needs. If anyone has any 2.5" - 3.5" brackets you'd recommend - let me know. I'd recommend storing your extra screws in a small bag and taping it to the drive mounting bracket. If you do need to return your iMac for repair, it's nice to have the original screws for the drive mounting as you'll want to replace the SSD with the original drive to insure there are no questions regarding warranty. <grin>. Ultra small ziploc (1" bags) are best.

    6. Putting it all back together was easy except the Vertical Sync ribbon cable. A pain in the butt for sure. I recommend A LOT OF LIGHT on the subject - remember you are trying to push the cable back into the connector - the monitor panel is only open about 3" because of the cable length and if you have big paws - it can be challenging without a lot of light. I used some tweezers that I have from my PC Mod'ing days - and that worked for me.

    7. All in all the swap took about 45 minutes - if I would do it again now that I know what to do - it would take about 15.

    8. As an FYI - if you like to open up your Macs - a great tool kit I'd recommend (from Lowes) is from Boxer. It is a 30 piece set of differing hex, star, phillips, standard, etc. screw drivers. I have not found a piece of gear in my setup that I haven't used this kit on. Here's a link to the set on Fry's Electronics website. http://www.frys.com/product/4292254
  13. Crunch macrumors 6502a


    Jun 26, 2008
    Crazy L.A.
    Nice investigative work. :) I am unclear as to the serial number of the 1TB drive that Apple puts into some iMac's (and not others, apparently? :rolleyes:)

    More specifically, System Profiler tells me that my iMac's 1TB hard drive has the following serial number: ST31000528ASQ.

    When I tried to figure out how I can order another one of those drives, all I could find is a 1TB Seagate drive with almost the same serial number: ST31000528AS.

    The only difference is the letter "Q" at the end of the serial number, which is the one that is in my iMac, whereas the drive without the "Q" is one that can be ordered through resellers of Seagate drives, such as OWC, for example.

    Bottom line: Are the two drives basically the same drive with the same specs, etc.?

    I'm still a n00b when it comes to Mac's and OS X, but I realize that Apple is a little "funny" when it comes to what components that it will allow in its products.

    Thank you very much! :)
  14. Crunch macrumors 6502a


    Jun 26, 2008
    Crazy L.A.
    I've found additional "types" of this particular hard drive from Seagate, which in all likelihood applies to that company's other drives as well.

    Besides the "main" model number, ST31000528AS, and the apparent OEM model no. for that drive in Apple computers, ST31000528ASQ, I have also found two additional letters that appear at the end of the main model number.

    For one, we have ST31000528ASR, which is $10 cheaper and advertised as "New Factory Refurbished" on OWC's page of Seagate hard drives. That seems to suggest that it is Reconditioned, Refurbished, Repackaged, or Re-something-or-other'd. There is only one drive left at the time of this post, so if someone wants to grab it up, the time is now. I'm not sure a $10 savings is worth buying anything other than a new drive, though.

    I had also found ST31000528ASO, but I cannot find the corresponding "spec" for the letter "O" at the end anymore. Oh well...

    How long is our ST31000528ASQ supposed to last? It seems to perform very well for me but there are a lot of problems posted by a lot of consumers about this particular model and I am used to my Hitachi drives, which are a lot quieter, to last forever, including even when bumped around quite a bit. :rolleyes:
  15. factcomp macrumors newbie

    Mar 2, 2011
    I just replaced the 1 TB drive in my 21.5" with an exact same model Seagate HD, only thing different is the Apple logo on the drive and the missing letter from the end of the serial number. Everything seems to work fine but after about a half hour the fan slowly starts getting faster. From everything Ive read, this should work if its the same model drive. Im not sure what the problem is, unless Apple has made it proprietary that only drives from Apple can be used. Any ideas?
  16. PLin, Mar 2, 2011
    Last edited: Mar 2, 2011

    PLin macrumors 6502

    Oct 9, 2003
    I have a 2009 27-inch iMac with a 1TB drive that System Profiler reports as ST31000528ASQ, and I'd like to upgrade it to a 2TB drive, but I've decided to hold off for now. OWC discusses the issues on the following webpage, and there's a lot of useful info in the comments:


    Even purchasing the correct temperature sensor cable to match the manufacturer of the aftermarket drive won't make the fans work properly. Only drives with Apple firmware can properly report the temperature to the logic board. Unfortunately, the cheapest 2TB Apple drive I can find online is over $500. The part number is 661-5175.
  17. Detosx macrumors regular

    Aug 27, 2010
    Assuming apple are just re-badging drives and flashing them with Apple firmware, it should be straightforward, in the case of my noisy 1TB Seagate drive in mid 2010 iMac, to buy a replacement Seagate for little money and flash it with Apple's firmware for that model. I have yet to come across a site that has Apple firmware, though, and, even if I did, I wouldn't be trusting enough to try it. There are workarounds out there but none of them terribly appealing at this point.
  18. Ceedub, Mar 24, 2011
    Last edited: Mar 29, 2011

    Ceedub macrumors newbie

    Jun 15, 2010

    I have a late 2009 27" Core i7 iMac with the same Seagate HD as you. I upgraded it to a 2TB Western Digital Black 2001FAAS. I attached the new temp sensor that I purchased for $19, (see blog entries #60 and #63 macsales) removing the proprietary Seagate HD sensor. Prior to the install my iMac would turn the HD fan at 990 rpm (idle). After the install, the fan is turning at 1100. I use SMC Fan Control software to keep the fan speeds where I want them (1500 for general work, 2500 RPM when running Handbrake. BTW, I also use iStat to monitor all temps and fan speeds.
  19. een1bhs macrumors newbie

    Mar 29, 2011
    You should try HDD Fan Control www.hddfancontrol.com if you want to control the HDD fan speed in relation to the HDD temp when the temp sensor no longer works (replaced drive) as it uses the HDD internal temp sensor and SMART to set fan speed and allows you to set the relationship between temp and fan speed.

    Also no command line needed and will run at startup and after sleep.

    Give it a go, works well.


  20. gerrysweeney macrumors newbie

    Oct 25, 2013
    I recently done an upgrade to a non-Apple HDD and posted a video. The roumers around special HDD firmware and fast fans is nonsense, you can do a very quick, simple and reversable mod to get HDD temperature sensing working on any brand of drive without special cables or software. Check it out....


  21. h4lp m3 macrumors 6502

    Jun 29, 2011
    New Orleans
    Am I correct in my assessment that any hard drive can be replaced with any of the newer models of the same brand?

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