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Adventure Encased in Aluminum

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iMac Intel 27" EMC 2390

Installing iMac Intel 27" EMC 2390 Dual HDD or SSD Drive

Installing iMac Intel 27" EMC 2390 Dual HDD or SSD Drive

1 - 2 uren

Difficult

Mijn probleem

I wanted my iMac to start up faster and run apps more quickly/smoothly. I was happy with the default 500 GB storage capacity, but the data seek and read/write performance were slower than I have become accustomed to on other computers equipped with solid state drives. So my plan was to add an SSD into the iMac, ending up with two drives, or at the very least, replace the hard disk with the SSD.

Mijn oplossing

The repair went more or less smoothly and by the numbers. I followed the picture instructions in the Install Guide provided here, with some minor changes.

Before opening the case or doing any hardware work at all, I backed up all my data to a 2TB USB external hard disk. I created two Journaled HFS+ partitions on the external drive using the Apple Disk Utility, each partition taking up half the total drive capacity. The first was for booting into the OS X installer, and the second was for backup data storage. If you're going to be using a flash drive for booting to the OS X installer, instead of an external hard drive, just make sure it is at least 8GB in size.

I did a simple file copy because the data I cared about was not all that large or extensive, but you could also use Time Machine's backup if you would prefer all settings to be preserved, including any obscure ones. I made sure to export my bookmarks from Chrome and Safari. I forgot to deauthorize iTunes, but it later proved not to matter, as I was able to re-authorize iTunes after installing the OS onto the new SSD without it using up another one of my 5 "authorized computer" allowances.

Then I downloaded the OS X Mountain Lion image I had purchased from the Apple Store, and used the free Lion Disk Maker app (http://liondiskmaker.com/) to load it painlessly onto my external drive's first partition and make it bootable.

For the SSD, I chose to try using a Corsair Force 240GB, because they're very fast, available at a good price point, and I've had excellent experience with them in the past. However, Force SSDs are not specifically certified for or guaranteed compatible with an Apple computer. Google searching seemed to turn up the fact that they will work fine, but I wanted to make sure through first-hand experience. So my first task was to ascertain that as quickly and easily as possible.

To do so, I put the SSD temporarily in place of the hard drive, using the hard drive's cables. I screwed it down into the 3 1/2" drive bay adapter tray that Corsair packages with it. Instead of using the adhesive squares (provided in the iFixit kit) to hold it down, I used the hard disk's screws to secure it down as firmly as I could. (Only 2 of the 4 screws had matching threaded holes with the correct spacing on the adapter tray, but it was good enough for testing.) After putting everything back together, I fired it up and the drive was detected fine and worked great. I installed OS X onto the SSD from scratch using the external hard drive I made bootable beforehand.

I enabled TRIM functionality in the OS using the free app called Trim Enabler (http://www.groths.org/trim-enabler/). For more info on what exactly TRIM is and does, and how it differs from an SSD's built-in garbage collection, check out the wiki page, http://en.wikipedia.org/wiki/TRIM.

One problem arose immediately, and that was that I could begin to hear significant fan noise inside the case. The longer the iMac stayed on, the louder it got. It turns out this is because the hard disk that comes with an iMac has a proprietary connector for the temperature sensor inside it that connects to the logic board via either a special cable (in pre-2011 iMacs) or a power cable with non-standard pin configuration (in post-2010 iMacs). The Corsair SSD (and many non-Apple hard drives) have no such connector (or special firmware, respectively) to accommodate the special cable's plug. So the iMac's SMC (System Management Controller) was erroneously cranking up the speed of the case's HDD fan to adjust for a temperature problem that didn't really exist.

Resetting the SMC, as described here: http://support.apple.com/kb/ht3964, proved to be only a temporary fix. The solution I chose to go with (which I believe to be the safest and gives the most nuanced control) was to pay $30 for the app called HDD Fan Control, available at http://www.hddfancontrol.com/. It worked immediately, to my great relief, and has a nice interface. It uses S.M.A.R.T. reporting to get temperature readings, which method theoretically uses more bandwidth or causes delays that Apple's proprietary method does not. However, in practice, I doubt the difference in performance (if any) is even noticeable, especially if upgrading from an HDD to an SSD.

I don't often recommend non-free software, but in this instance, it seemed like the best choice, considering we're dealing with something as important as system cooling. However, this software is only necessary if you are replacing the original hard drive with a non-Apple drive (as I was, temporarily). If you are replacing an optical drive with another hard drive, or adding an SSD without replacing anything, then you won't need any fan control app. The temperature sensor issue apparently only affects the hard drive connected to the primary SATA channel.

Then I proceeded to optimize the system for use with an SSD, with tweaks I found online that either increase its speed or decrease the amount of unnecessary wear it receives over time, prolonging its life. For details, see here: http://blog.alutam.com/2012/04/01/optimi.... I wouldn't recommend doing the tweak that disables the swap file unless you have enough system memory installed for it not to cause problems. That means at least 4 GB of memory if you don't usually have a ton of apps open at one time, and preferably at least 8GB otherwise.

In the above-linked article, it mentions that implementing the RAM drive option for temporary files made the author notice a 2-3 second increase in shutdown or restart times. However, I do not think that any extra delay was due to the RAM drive tweak. For me, it turned out to be an issue inherent to OS X 10.8.2 and 10.8.3, wherein certain processes don't shut down as quickly as they should on their own. I was able to find a fix for this, however, at this location: http://forums.macrumors.com/showthread.p...

Now my iMac shuts down in about 2 seconds with regularity, which continues to be awe-inspiring to me. :)

After all this, I opened the case back up and proceeded with the rest of the upgrade described in the iFixit Install Guide. So now I have both the SSD and my original hard drive in the same machine, both working great. This time, I did use the adhesive squares to secure down the SSD. After several days, once I felt sure that the new hardware would continue working without any hiccups, I decided to try combining the two drives into a single Fusion Drive. I used this site to help me set it up: http://blog.macsales.com/17624-os-x-10-8...

**You will need the image file inside the 10.8.3 or later OS X Installer app in order to get a version of Disk Utility capable of making a Fusion Drive.** I made a backup image first, which proved to be a good idea. I decided afterward that I preferred the flexibility of being able to decide manually which files should be on the slower hard drive, with the aid of symbolic links when necessary. So I undid the Fusion Drive, and re-imaged the SSD with the backup I had created. But the Fusion Drive array did perform as advertised while it existed.

Overall, a very pleasing outcome and an interesting adventure implementing it. It took me about 5 1/2 hours, but much of that was spent experimenting or copying data, etc. If I were to do the procedure again, it would take me much less time, probably in the neighborhood of 20 minutes for the hardware stuff, and an hour or two for the data part.

Mijn advies

1. Make sure you have all your ducks in a row before you start messing with any hardware. This includes:

- Always back up your data before doing anything else!

- Make a flash or external drive bootable with the OS X Installer beforehand and *test it to make sure it boots*

- Avoid any cramped work spaces or unstable surfaces like wobbly tables or trays. They can result in parts falling off onto the floor or scratching up against other parts, etc.

- Clear your work space of any clutter (and wipe up any dust or dirt)

- Get all your tools laid out and ready (clean them first if needed, get out the specific screwdriver tips involved, etc). The less time you spend getting or preparing tools while the case is open, the less time airborne debris will have to settle into it.

- Wear an anti-static strap if you have one (I didn't use one)

- Unplug all cords, and especially the power cord, from the iMac

- Keep any pets away from the work area. The static charge in pet hair is very dangerous to sensitive electronics.

- Don't pet burning dogs.

- Move any food or drinks well away from the work area.

- Avoid working in any hot areas or under hot lights, as this can risk making you sweat enough for it to drip down into the hardware. Plus, sweaty hands don't have good grip and can leave more of a mess on the glass to have to wipe off.

2. Be very careful when using the suction cups to lift the glass up away from the monitor screen. It didn't happen to me, but I have heard from two different friends of mine who are Apple Store employees that it is very common for inexperienced or inattentive people to crack the glass by lifting it improperly. They didn't tell me this until after I was finished, so I get the impression they may have been making bets with each other about whether I would crack the glass if left to my own devices. :p

Place the top edge of the iMac facing toward you. When you position the suction cups, simply mimic the relevant iFixit Install Guide photo exactly. Place at least one finger of each hand (I used my pointer fingers) on the metal of the case on either side of the iMac directly behind the glass plate (or "below" it, if you're looking down at it), while the other fingers are gripping the ring handles of the suction cups, so you have more control over how much force you apply. It takes less than you might imagine if you've never done it before.

Push downward toward the table top (or other work surface) while your other fingers lift upward, curling toward your palms. Try not to let the glass plate slide forward or backward before taking it out or while putting it back in, as this can damage the grounding foil between it and the lowest two (of the eight) screw holes on the sides. This happened to me and, while it doesn't appear to have caused any functional harm, it still bothered me, as I would prefer to keep my iMac in as close to factory condition as I can.

3. Move slowly in general and perform all tasks with deliberate caution, even simple ones you've done a hundred times before.

4. After removing the glass, leave the suction cups fastened onto it and place it face-up onto a soft, flat surface that will not mar or scratch it, such as an anti-static mat or two thick strips of styrofoam, one placed under each side. Or you can just lean it against a wall, as long as you are certain it won't slide and fall flat. Either way, face its front (i.e. outer) side upward to minimize dust getting on the back side, which will be the side against the LCD screen face when reinstalled.

5. Turning off the air conditioning system in your house, apartment, or workshop will help to reduce the amount of mobile dust and debris in the air, if working indoors.

6. If a part doesn't immediately snap into place or fit quite right, don't force it! Pull it back out, examine it closer, reposition if necessary, and try again. If you're doing it right, all parts should be removable easily enough, and go back into place even easier.

7. It can be difficult to remove the 8 screws on either side of the LCD display panel that hold it in place. The strong magnets that hold on the front glass panel try to "grab" the screws away from your screwdriver. This is even more of a problem when trying to put them back in. I found it helpful to put the screw on the end of the screwdriver, which is weakly magnetized so it should hold onto the screw, then position the screwdriver so that the screw is angled away from the nearest magnet(s) as much as possible, then lower it down toward the magnets. Watch the spacing carefully. It sucks having to undo screws and remove the LCD panel again just to go find a rogue screw you dropped.

Once you get the screw down below the plane of the magnets, arc your hand slightly so that the screw is angled back toward the threaded screw hole. At this point, it should be low enough that the magnets can't pull it away from the screwdriver's tip. If the magnets try to grab a hold of the screwdriver tip itself, then put more distance between it and the magnet(s) by tilting it away from them but keeping the screw tip aimed toward the center of its hole.

8. One of my aforementioned Apple Store friends also warned me to be careful, before lowering the glass back into place when done, to remove any dust or debris that might have been attracted onto the LCD screen or the back of the glass plate during the proceedings. Mostly I was able to blow off any such particles with my breath alone, but in a few instances I needed to use a soft, dry, lint-free cloth (like the type of cloth used for cleaning eye glasses) to detach some stubborn particles.

When I used the cloth, I barely had to touch the screen(s) at all, i.e. no pressure or force was required. After the second time I opened the case up (to add the original hard drive back in), once I returned the glass and powered it back on, I had an issue with a few black spots being visible when the LCD lit up, and thus had to remove the glass again, just to clean away some specks I wouldn't have missed if I had spent a little more time checking.

9. If you are simply replacing the stock Apple hard drive with an SSD and your computer is a pre-2011 iMac, there is going to be a spare cable left dangling inside the case (the proprietary temperature sensor cable). This is normal and should not cause any problems, although you may wish to either remove it or tuck it under something to keep it from moving around once the case is closed up again. Any resultant abnormal fan noise can be resolved by the app mentioned in the "My Fix" section above. Ignore this point if you are adding an SSD or HDD and not replacing the original Apple drive.

10. Keep any surplus screws or mounting hardware (as will result from replacing the main hard drive instead of adding the SSD alongside it). You may end up needing those extra parts later.

11. I didn't need to, but you may wish to take the opportunity to use compressed air to blow any accumulated dust out of the system or fans while the case is open. Doing so may prolong the Mac's operating life if a lot of dust has accumulated. Make sure to move the glass front panel and LCD display panel a good distance away before you do, though.

12. You will need to partition and format the new drive before it can be selected as a target for installing OS X. Kind of a no-brainer, but it briefly freaked me out a bit 'til I had that "Oh... Right." moment.

13. Whenever you're not using both hands to perform some task, always keep your unused hand resting grounded somewhere on the metal outer casing of the computer when performing work inside it.

14. Always clean all your tools when done, and put them away in a place specially designated for them, so you can always find them, in good condition, the next time you need them.

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