It goes without saying that the more memory your Mac has access to, the smoother it will run. This is particularly true in the age of 64-bit operating systems like OS X Lion and apps that can take advantage of all available RAM you can throw at it. But do you know where to find the best deals on memory, and does it make sense to pay more?

For many Mac owners, buying extra memory with a new system is as simple as clicking an extra box in the build-to-order section while checking out at the Apple Online Store. After all, it’s fast and convenient -- your Mac will arrive with extra RAM already installed and ready to work, no muss, no fuss.

However, longtime computer users know that Apple isn’t exactly the best bargain in town when it comes to memory (that’s putting it mildly -- see below), and as Toni Tennille used to sing to The Captain, “You better shop around.” So without further ado, let’s take a look at how and where to make your next RAM purchase.

What Kind of RAM Do I Need?

Finding out what type of RAM you’ll need to buy is the easy part. Head to the Apple menu on any Mac OS X system, select About This Mac and click “More Info.” For systems running OS X Lion, you’ll see a new tab for Memory like the one above, which shows exactly how much RAM you have installed, what kind your system takes and how many slots are available or in use. There’s even a handy “Memory Upgrade Instructions” link that opens an Apple support document in your default browser to walk you through the process.

For pre-Lion Mac OS X versions, the “More Info” button leads straight to the classic System Profiler shown above -- in the sidebar is a section for Hardware and about midway down you’ll find a “Memory” option which will display the specs for each piece of memory installed, including where it resides, how big it is and what type and speed you’ll need. Make a note of these before you continue.

How Much RAM Can I Handle?

If you have a recent Mac still sold by Apple, you can usually head to the web page for that specific model and click on the “Tech Specs” link -- under “Processor and memory” you’ll usually find the maximum amount of RAM supported for that model. For example, the current 27-inch iMac with Thunderbolt comes standard with 4GB of RAM but is capable of supporting up to 16GB of 1333MHz DDR3 memory using its four slots (two of which are already used, but can be swapped out).

While most RAM vendors offer online tools for determining what kind of memory you’ll need, the easiest way to get answers is by using a free System Scanner provided by Crucial, one of the leading providers of RAM and solid-state drives for computers. Download the tiny Crucial System Scanner, double-click to launch it and your browser will open with complete details on how much memory you can install. The tool even provides you with an immediate price quote if you want to buy it straight away.

Does It Matter What Kind I Buy?

Longtime Mac users have probably had a run-in with bad RAM at some point in their storied history with Apple computers. Older Macs in particular were often notoriously finicky about the quality of memory used, but keep in mind that as processors have gotten faster and components have shrunk in size, today’s Macs can be even less forgiving about cheap, poor quality RAM -- which is more likely to cause problems ranging from kernel panics and application crashes to potential data corruption.

The important thing to remember is to match the RAM’s speed with what your specific model is asking for. Using memory faster than your computer can handle won’t help make the system any faster -- assuming it recognizes the RAM at all.

Where Can I Buy RAM?

Because computers are so entrenched in our everyday lives, you can buy memory for them just about anywhere these days -- even retail giants like Walmart offer RAM upgrades on their website (you won’t be able to walk in and grab them, unfortunately). Locally, your best bet is usually the nearby Best Buy, although you should brace yourself for a slim selection and inflated prices. Smaller computer shops in your area might also be able to help, but there’s no doubt that buying online is the best choice.

While there’s an almost limitless choice of options for buying RAM online, it’s worth a stop at Amazon.com first, especially if you have an annual $79 Amazon Prime membership. That elite club will net you free two-day shipping with no sales tax in most areas, and those savings can often be significant since many e-tailers pad “shipping and handling” costs to make up for slim profit margins on many products. Amazon doesn’t make it easy to find what you’re looking for, but their prices can often be worth the trouble.

Bargains can also be had with online resellers such as NewEgg or Fry’s, but neither of them get high marks for being friendly to Mac users, since they cater mostly to DIY PC users favoring Microsoft Windows or Linux. That said, both sites are worth a quick stop while researching RAM prices as long as you know in advance what you’re looking for, and their daily deals mean you might turn up a real bargain now and again.

On any given day, eBay offers a huge supply of memory from sellers small and large, but you’ll want to approach with caution. There are plenty of third-rate component suppliers from the Far East and plenty of sellers with lower scruples who care little about over-promising and under-delivering. Even if you manage to get your money back for bad RAM, the headache may not be worth it. Check a seller’s feedback carefully and when in doubt, research the memory you’re considering buying via Google, Bing or Yahoo. It also pays to fire off an email to the seller with any questions -- the faster they reply with helpful answers, the more legitimate they often are.

Buying Online from RAM Specialists

When it comes to buying RAM online, the vendors who make it their business to specialize in such hardware are usually easy to spot. Most of them make available a variety of online tools to make sure you find exactly the right memory for your system, with frequently updated databases culled from every computer maker under the sun. Thankfully, long gone are the dark days when finding Mac RAM was often a challenge.

Even though our own 27-inch 2.93GHz Core i7 iMac from mid-2010 is already maxed out at 16GB of RAM, we decided to look at a handful of online vendors to see who has the best deal at this writing -- including Apple’s own build-to-order option.

The aforementioned Crucial is often considered one of the better places for buying RAM upgrades, if only because they historically specialize in memory, although their selection has expanded in recent years to include solid-state storage and other accessories as well. Crucial offers an 8GB Kit (each with two 4GB modules) for our iMac for $59.99, so we’re looking at a mere $126.88 out the door (shipping is free, plus $6.90 for sales tax) for a total of four 4GB modules.

Other World Computing is a popular Mac-centric choice for buying hard drives, optical drives, memory and other accessories and being based in Illinois, they’re often a good choice for those living in the Midwest or on the East Coast if time is of the essence. However, in our case, 16GB of iMac RAM worked out to $147.94 including $1.95 “SuperSaver” shipping (sales tax wasn’t applicable in this case) -- making Crucial a better bet by more than 20 bucks.

Another Mac-friendly Illinois vendor is Ramjet, a longtime memory source with a lifetime warranty. Unfortunately, they weren’t a great value for our iMac, with the same 16GB option priced at a whopping $299.99 plus $7.99 for UPS “Economy” shipping. However, keep in mind that RAM prices fluctuate and many vendors offer their best deals on smaller size chips since they tend to be more common.

Finally, hopping back on the budget bandwagon, Data Memory Systems (DMS) worked out to only $144 with free shipping and no sales tax from New Hampshire, making it our second best option at this time.

Apple.com: Sticker Shock!

By now you’re probably wondering just how bad could Apple’s own RAM prices be after seeing how wide-ranging a memory upgrade can be purchased for elsewhere. While our mid-2010 iMac isn’t available new anymore, we priced a 16GB RAM upgrade as part of a build-to-order option for a comparable 27-inch 3.4GHz Quad-Core Intel Core i7.

Are you sitting down? The 16GB RAM upgrade -- which is the exact same 1333Mhz DDR3 SDRAM used by our 2010 model -- would cost an additional $600 when purchased direct from Apple. Given that installing your own RAM only takes a few moments and almost no technical skills, would you save more than $450 by buying from the likes of Crucial and doing it yourself? We thought so…

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