Memory upgrade for iMac

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pvhansen@tfon.com
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Memory upgrade for iMac

Post by pvhansen@tfon.com » Sat Dec 06, 2014 12:10 am

I'm upgrading ram on my late 2009 21.5 in iMac (mod.10,1). It currently has 4G (2x 2G and two empty slots), and I wish to go to at least 8G. What are the configuration requirements for the ram upgrade? Can I add 2x 4G and leave the 2x 2G, or do all of the memory sticks need to be of the same value. If they need to be the same, is there an advantage to adding 2x 4G and removing the 2x 2G, or would it be the same to add 2x 2G to the existing ram? Can I fill 3 slots?

Another question; Ram Jet's memory is nearly twice the price of Crucial through Amazon ($120 vs $68 for 8G). Is there a significant quality difference between the two? Ram Jet is said to be "non-stacked"; don't know about Crucial.

Thanking you for your advice,

Paul H

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Stephen Hart
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Re: Memory upgrade for iMac

Post by Stephen Hart » Sat Dec 06, 2014 9:43 am

A particular model may require or work better with RAM in pairs. Any given Mac also has a maximum amount of RAM the CPU can address. If your Mac has four slots, you should follow those guidelines, but can otherwise mix and match.

The best way to configure a RAM upgrade is to go to one of the main sellers directly, and use their guides. If you then want to comparison shop, you can, but make sure you're buying the same speed RAM.

I have bought RAM from Other World Computing several times and never had a bad stick. They may not be the cheapest, though. Here's their page for your model.
http://eshop.macsales.com/shop/memory/iMac/DDR3_21.5_27

Amazon has an excellent return policy, even if the thing you buy doesn't come directly from them.
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JerryFreilich
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Re: Memory upgrade for iMac

Post by JerryFreilich » Sat Dec 06, 2014 11:46 am

I've always had perfect success with Ramjet and have used them for many years. I am not sure about the non-stacked distinction (I think this is important in certain models where the height of the chips is important to fitting the available slot) but I think you need to make sure you have exactly the right size chips for your particular Mac model.

If I am correct, using MacTracker it says for your machine:
Maximum Memory 32 GB (Core i5 or Core i7 Actual) 16 GB (Apple)
Memory Slots 4 - 204-pin PC3-8500 (1066 MHz) DDR3 SO-DIMM

So you can move it up to 8 GB or 16GB.

You know, I've never seen such a large price differential between the high and low as you mention... I had thought it was always differences between different speeds or models of chips. Maybe I'm just behind the times....

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Stephen Hart
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Re: Memory upgrade for iMac

Post by Stephen Hart » Sat Dec 06, 2014 12:01 pm

You know, I've never seen such a large price differential between the high and low as you mention... I had thought it was always differences between different speeds or models of chips. Maybe I'm just behind the times....
RAM prices are always volatile. That means that one vendor may be able to offer a lower price (or have to offer a higher price) because of buying in bulk at the right or wrong time.

Traditionally, Apple's RAM upgrades when buying a Mac range from expensive to really expensive. But when I bought my retina iMac, there wasn't much difference between Apple's upgrade and OWC's prices. (Note that Apple often replaces RAM, while with all third-party suppliers, you're buying new RAM and get to keep the old RAM. OWC, and probably others, offers trade-ins.)
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Richard Serkes
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Re: Memory upgrade for iMac

Post by Richard Serkes » Sat Dec 06, 2014 12:13 pm

If you decide to add RAM to the available slots make sure the slowest sticks are in slots 1 and 2. The CPU will read the speed of the sticks in these slots and make the remaining sticks run at the same lower speed. Putting the faster sticks in slots 1 and 2 will "overclock" the slower sticks and can cause problems.

Based on the age of your Mac I'd bet the new sticks will be faster than the old ones so just leave the old ones where they are and you'll be good to go.

Oh, before you open your Mac put on an anti-static wrist band and connect it to a ground. OK, I know that sounds a little over the top but I never open a computer without grounding myself first.
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pvhansen@tfon.com
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Re: Memory upgrade for iMac

Post by pvhansen@tfon.com » Sat Dec 20, 2014 12:26 pm

Thank you all, for your help and advice with my project.

I got the 2x 4 G Crucial memory from Amazon at a significant price reduction after determining that it was the same as that offered by Crucial. Speed was rated at 1066 MHz for existing and new. Installed and working well, with significant performance improvement (e.g. web pagers download at least 2x faster).

One issue that was not mentioned in discussions of the installation process (which was generally straight forward) is dust accumulation in the slots not occupied before the installation. There was quite a bit of the stuff in the grate and the slots, which was easily removed (while keeping myself well grounded) with mini attachments that came with a 'Dust Devil' hand vacuum.

Cleaning the ventilation grate is obviously something that needs to be done periodically. Are there any other anti-static measures that need to be taken other than doing it while grounded and on a higher humidity day?

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Stephen Hart
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Re: Memory upgrade for iMac

Post by Stephen Hart » Sat Dec 20, 2014 2:54 pm

Cleaning the ventilation grate is obviously something that needs to be done periodically. Are there any other anti-static measures that need to be taken other than doing it while grounded and on a higher humidity day?
The dust accumulation is likely because the RAM door is part of the air intake for that iMac. I seem to remember that as well.

You shouldn't have any issues with vacuuming the bottom edge of the iMac with any vacuum that has a brush attachment. Just leave it plugged in. Then all the aluminum will be well grounded. Don't spray canned air into the iMac. (Despite what I see on the web, even though some dust will come out, other dust will be driven into the innards.)
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BarbJ
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Re: Memory upgrade for iMac

Post by BarbJ » Mon Dec 29, 2014 12:37 pm

This is a related question about memory upgrades. I'm thinking of purchasing a new iMac. Why does 32 gb of ram cost more than twice the price of 16 gb? Why couldn't I just buy it with 16 gb and then add another 16 gb myself to save on the price of memory?

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Stephen Hart
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Re: Memory upgrade for iMac

Post by Stephen Hart » Mon Dec 29, 2014 2:28 pm

BarbJ wrote:This is a related question about memory upgrades. I'm thinking of purchasing a new iMac. Why does 32 gb of ram cost more than twice the price of 16 gb? Why couldn't I just buy it with 16 gb and then add another 16 gb myself to save on the price of memory?
I addressed the cost issue above in this thread. Apple buys RAM in bulk, then sets their upgrade price. Check the particular model you're interested in. It may ship with all four slots full. You can replace the RAM in two slots or four. How much you can save depends on who you buy from and what the price is on the day you buy.

More general information for this thread:

You can upgrade RAM on a new iMac.

To those instructions, I would add the following:

1. Make sure you have plenty of room to turn the iMac and lay it down. Take special care laying the iMac down and picking it up again. This is especially necessary if it's a 27" iMac. They're big and awkward.
2. Don't unplug the iMac cord from the wall.
3. Don't unplug the cord from the iMac until after you've turned it over and have everything you need at hand and aren't going to move anywhere. This especially necessary if you have carpeting. This will ensure that you've discharged any static electricity into the aluminum case and then to ground. If you have to, unplug the iMac from the wall, move it, then plug it back in to turn it over.
Alternatively, you can just touch some other piece of equipment that is metal and is known to be grounded.
(Even after it's unplugged, the iMac case can probably absorb a lot of static safely. While Apple doesn't say they design the iMac to handle static when unplugged, their instructions don't include any static cautions.) You may also want to use a grounding wrist strap.


Though it seems to depend on whim, Apple sometimes blames RAM for any problem you take the iMac to them for. If you replace RAM yourself, it's a good idea to keep the old RAM and reinstall it if you ever need to take the iMac to Apple. Having that other RAM around can also be useful for troubleshooting.

It's possible for RAM to not seat perfectly, so if you notice any issues after replacing RAM, remove the new RAM and reseat it.
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BarbJ
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Re: Memory upgrade for iMac

Post by BarbJ » Mon Dec 29, 2014 7:57 pm

Thanks Steve! Hope we did the right thing. We ordered the computer with 8 gb and we will order 32 to replace it from OWC. The OWC video makes it look easy to change the RAM in this computer. Thanks for the extra info as well.

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