Answer

If you are having performance issues, software “hangs” or random crashes—we recommend you run a memory test. For the Mac OS, a popular tester is Rember, which can be found here:

http://www.kelleycomputing.net/rember/

Set Rember to test “All”, and check the box next to “Infinite” number of loops, and let the test run for at least half an hour. Since Rember is running from your desktop, it's important that you shut down all applications before you run the test. If you have any programs open, the test will be a lot less accurate.

If Rember finds errors with your RAM, you may need to replace it. To request an RMA, fill out the online request form, or contact Customer Service for your region.

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If you aren't sure what Mac model you have or what kind of memory it takes, you can get your System Profile through the Apple menu. The profile will tell you what kind of memory and how much memory is in your system.

1. Open the Apple menu, and then select "About This Mac".

2. The "About This Mac" screen opens. Click the "More Info..." button.

3. The Hardware overview screen will open. Click on "Memory"

4. The Memory Slot screen will now apear and show your current memory configuration, what kind of memory is installed, and there will also be a link to memory upgrade instructions for your model.

If you want to make it really easy for yourself however, our Mac System Scanner will do all this work for you.Just download the tool and we’ll show you what memory you already have, and what memory upgrades are available.

You can also go through our Mac Memory Selector and manually pick out your system from menus, for a list of all compatible upgrades Crucial offers.

Both the Mac System Scanner and Mac Memory Selector can be found on our Mac Memory page.

Answer

If your Mac is getting a little older, you may notice that it doesn’t run as fast as it used to.  A memory upgrade from Crucial.com can give your Mac the boost it needs – for surprisingly little money.

The amount of memory you need to optimize your computing performance depends on your computer model and what you use it. Overall, we recommend a minimum of 8GB of RAM for systems with the capacity. Learn more from these guidelines.

Answer

Single data rate (SDR) SDRAM is the older type of memory, commonly used in computers prior to 2002.

Double data rate (DDR) SDRAM hit the mainstream computer market around 2002 and is a straightforward evolution from SDR SDRAM. The most significant difference between DDR and SDR is that DDR reads data on both the rising and falling edges of the clock signal, enabling a DDR memory module to transfer data twice as fast as an SDR memory module.

The generation after DDR, called DDR2, began to appear in mid-2004. DDR2 is faster than DDR, delivering bandwidth of up to 8.5 GB per second. Frequently, DDR2 based systems can use memory installed in pairs to run in "dual channel mode" to increase memory throughput even further.

The most recent generation of memory technology, DDR3, began to appear in systems in late 2007. DDR3 is the next evolutionary step beyond DDR2 and operates at lower voltages, which means it consumes less power, and it can transfer data at rates up to 12.8 GB per second.

Your Mac supports only the memory generation that it first shipped with. You cannot mix and match SDRAM, DDR, DDR2, or DDR3 memory in a Mac. The different memory types don’t function together, they will not even fit in the same sockets.

Because of this, you need to make sure that your upgrade is of the same memory generation as the memory that shipped with your Mac. The easiest way to find compatible memory is to look up your system in Crucial's Memory Advisor tool, that will list only compatible memory for your Mac.

If you don't know the exact model of your Mac, the Crucial Mac Scanner will automatically detect your system configuration and give you a report on which upgrade is right for you.