by Dustin Sklavos, California USA
RAM (Random Access Memory) has been widely regarded as the cheapest, easiest way to improve computer performance for the past decade at least. It's one of the three main components responsible for your system's day-to-day performance, alongside the CPU and the oft-forgotten hard disk, and too little of it can be a serious bottleneck.
But choosing how much you want in a new notebook may be difficult enough, and the terms "DDR" and "DDR2" could very well mean next to nothing to you. This guide is here to help clarify that.
Upgrading RAM can be an equally difficult task, and you don't want to be the pesky customer at your local retail store that says, "I need more RAM" but doesn't know what kind to get. Knowing the internals of your computer is always important, but with RAM it becomes especially so. This guide will also help to clear this up for you.
Note that the terms "memory" and "RAM" are used interchangeably in modern use, and will be used interchangeably here as well, though "memory" will likely be seen more.
TYPES OF MEMORY
- 200-PIN DDR SO-DIMM
This is by and large the most common type of notebook memory available. It comes in three speeds; below I've listed the designations you'll see them in:
99% of notebooks produced at the time of this article's writing use DDR333 200-PIN SO-DIMMs. The difference in speeds offers middling performance improvements. If you're using a Celeron M, older Centrino, or AMD based notebook, it will be using this type of RAM.
- 200-PIN DDR2 SO-DIMM
This is becoming much more common, and is also the least expensive type of notebook memory available. It comes in two speeds; below I've listed the designations you'll see them in:
Almost all newer Centrino notebooks use DDR2 memory, and the only notebooks I've seen PC3200 DDR2 show up in have been HPs. Almost all DDR2-based notebooks use PC4200.
One major benefit to point out about DDR2 against the other types is that it runs close to a full volt less than DDR does, so DDR2 is also more battery friendly, which may be something to keep in mind. DDR2 also tends to be less expensive.
- 172-PIN DDR MICRO DIMM
These show up pretty much exclusively in ultraportables and periodically in thin-and-lights. These tend to be pretty expensive. They appear in the same designations as conventional DDR SO-DIMMs, but are uncommon and tend to be difficult to get.
Sony seems to really like these; I had a Vaio TR2A that used them, for example.
- PC100 / PC133 144-PIN SO-DIMM (LEGACY)
Most older notebooks (at least three years older) use these. No new notebooks come out using this technology, as it's much slower than what's available today and more expensive.
SINGLE VS. DUAL CHANNEL
Dual channel memory has been enjoyed on the desktop for years now, but only recently has surfaced in notebooks within the last year with the advent of Intel's Sonoma platform in Centrino notebooks.
Running your memory in dual channel basically adds a substantial amount of bandwidth to the memory, but must be done using two identical sticks of memory. I've read reports of people using sticks of different sizes (but identical speeds) in those Centrino notebooks and still running their memory in dual channel mode, but you may want to play it safe and go for two matching sticks.
As of this article, only Centrino notebooks running DDR2 memory can operate in dual channel. All other notebooks run their memory in single channel.
What is worth mentioning about dual channel operation is that while it can net substantial performance benefits in desktop computers, even Intel's newest Centrino platform still can't fully utilize the increased memory bandwidth. Because of this, performance benefits of operating in dual instead of single channel are generally negligible and not worth the expense of trying to get two matching sticks. The only real benefits I've seen to running a Centrino notebook in dual channel are for the GMA 900 in gaming and bandwidth intensive multimedia tasks, such as video encoding, but even then these performance benefits are still fairly marginal.
CAPACITIES AND WHAT YOU NEED
We've spent all this time talking about what kinds of memory there are, talking about speeds and channels and all that, but the most important thing is really the capacity.
Notebook memory is generally available in the following capacities per stick: 128MB, 256MB, 512MB, and 1GB. Of course, the farther you go back in time, the smaller the capacities you'll find, but realistically I shouldn't even be mentioning 128MB or 256MB at this point.
I'll list the total amounts of memory and what I recommend that amount for:
512MB -- This is the minimum amount for proper operation of a computer. Yes, theoretically, your computer can operate with 256MB, but Windows XP positively hates that. What's important to note is that anything Windows needs to store in memory but can't due to a lack of capacity will get stored in a swap file -- on your hard disk. In a desktop computer this is bad enough, but at least desktops have semi-fast hard disks standard. It hurts, but it won't totally kill you. But notebooks don't have that luxury. Having to switch to the swap file on the hard disk will cause your system to slow down substantially, and worse, will eat battery life because the hard disk has to spin up and be accessed more frequently at its grueling slow pace. For this reason, 512MB is the bare minimum for any notebook, but also should prove satisfactory for most tasks and even some mild gaming. Note that if you're using an integrated graphics part like the GMA 900 or ATI Radeon Xpress 200M, they're going to be stealing out of this for gaming, and that will cripple your gaming performance. Worse, while the GMA 900 only takes as much as it needs, the 200M uses a set amount of memory. A notebook with 512MB of memory and a 200M will only have 384MB left for the system unless the 200M is reconfigured to draw less.
768MB -- Fairly ideal if you're on a budget but using an integrated graphics part.
1GB (1024MB) -- Probably the most ideal amount of RAM a computer can have at this time. 1GB assures a smooth computing experience with all tasks, and I'd consider it the minimum for any serious multimedia work (video or graphic editing).
1GB+ (more than 1024MB) -- Generally unnecessary for anyone but multimedia enthusiasts.
A WORD ABOUT GRAPHICS
I mentioned briefly in the previous section that having 512MB of RAM with an integrated graphics part can slow your system down, and it can. These parts borrow from your main system memory since they have no dedicated memory of their own; because of this, they will eat some of your bandwidth but worse, they will eat some of the system memory that would ordinarily be used for other tasks. But there are also non-integrated parts that still share system memory, and I'll go over those briefly here.
Intel's Extreme Graphics, Extreme Graphics 2, and GMA 900/950 parts all dynamically adjust the amount of memory they share from the system, taking only as much as they need at any given time. But when you're gaming, they're going to be taking all they can -- the Extreme Graphics parts will steal 64MB, and the GMA parts will steal as much as 128MB, so you can subtract that from your total amount of memory to determine how much memory is left over for the actual game you're playing.
ATI's Radeon Xpress 200M and its older integrated graphics parts (Radeon 7500/9000/9100 IGP, 320M/340M IGP) use a set amount of system memory and this does not dynamically change. It must be set in the BIOS of your notebook (see your manufacturer's site for details on how to do this). Because of this, while an Intel part which will draw as little as 8MB of system memory when not in use, the ATI part will always be drawing the same amount (usually 64MB or 128MB) from your system memory, and this can severely cripple performance.
Let's confuse things a little more. ATI and nVidia both have discrete notebook parts that draw on system memory to increase their effective video memory. ATI calls their technology "HyperMemory"; nVidia's is called "TurboCache." Two different words for the same thing, barring slightly different implementations. You'll want to review my GPU article to learn more about these.
Suffice to say after all this stuff, though, if you're using an integrated graphics part other than an Intel part, you're likely going to want to upgrade beyond 512MB of RAM. Even just going up to 640MB would still be sound; 768MB might be more ideal. And if you're going to be doing mild gaming on your Intel part, you may also want to make this upgrade.
Of course, if you're not gaming at all and have an integrated part from ATI, you'll want to go into your BIOS (again, see your manufacturer's site for details) and just set the amount of memory it draws to its bare minimum.
Okay, let's say for a moment you're one of those frustrating customers that doesn't know what kind of memory your notebook uses. Well, you don't want to be that guy (or girl), you want to be able to know exactly what you need so the clerk behind the counter doesn't get frustrated with you. I've been that clerk, and we talk about you behind your back because you frustrate us. Just telling them you have a Powerbook or a Presario doesn't help.
Everest can help. If you go to www.lavalys.com and download Everest Home Edition, it will identify exactly what kind of memory your system uses. Unless you're already familiar with memory (and thus don't need a guide like this), you'll want to get the same speed of memory, and Everest'll tell you what that speed is. Faster stuff usually will work, too, as long as it's the same type, but there's no guarantee.
If you've read this far into the guide, you should know what kind you need and how much you need. Which is great -- if you're upgrading an old notebook. You're just about done.
What you do need to know is that 99% of notebooks only have two slots for memory, and recent ones max out at 2GB (older ones may not support 1GB sticks). You're going to want to find out how many slots you have open; again, Everest will tell you. More than likely, you'll have to remove an existing stick and replace it with a larger one, and this is frustrating, but you'll cope.
Now, if you're buying a new notebook, well, life isn't terribly consumer friendly for you. Notebooks today usually don't come with anything smaller than 256MB of RAM, and they generally don't come with any stick smaller than that (if you buy a notebook with just 256MB of RAM, you'll usually have a slot free). But if the notebook comes with 512MB of RAM, you have a problem. Odds are -- and this is especially true if the notebook is a Centrino -- it will be in two 256MB sticks, so when you go to upgrade, you'll be buying at least a 512MB stick and your upgrade won't be as big as you like. If the notebook comes with a full 1GB of RAM, I all but guarantee you it's in two sticks of 512MB, so when you go to upgrade it, you'll be buying 1GB sticks. But if it comes with a full 1GB of RAM, this probably isn't going to happen for a while yet.
I'd like to point out right now, for those of you looking forward, that there are many benefits to DDR2 based notebooks. First, DDR2 is on average $10 cheaper for the same amount of memory as regular DDR. Second, AMD is switching to using DDR2 for its chips in the future (about six months from now or so), so the last bastion of DDR is taking a hike. You can also be fairly confident that even Intel's Celeron M notebooks will switch to DDR2. DDR2 is the future. Keep that in mind.
That said, I'm using a regular old DDR notebook, and I expect that even if I upgrade it, my next notebook could still very well also use DDR. These transitions also tend to take some time to come through, so DDR will still be with us for a while yet.
So now you've got all this information, but what manufacturer do you buy your memory from? RAM can be bad and bad RAM is a hell for a computer, because it can manifest in all kinds of scary ways. Your system may become substantially less stable. Your display might corrupt. Data might corrupt. Of all the things to go bad in your system, this is probably one of the worst, so you want to buy from a reliable brand.
First, don't buy OEM. Don't get the cheap stuff from someplace like Fry's. The stuff that comes packaged in stores like Best Buy, from manufacturers like Kingston and PNY tends to be perfectly fine. If you're ordering online (always an excellent choice), you'll want to buy from companies like Crucial or Corsair. I'm sure people in the forums will chime in on their favorite brands, so be sure to check there, too, for suggestions.
Some notebooks just plain don't like certain brands, and while this really isn't as common a problem as some alarmists would have you believe, it doesn't hurt to check the forums here and see what brand other people with your notebook used.
I admit, even I'm a bit stunned with how complex memory can be. There are enough different types out there to make things confusing, and it just gets more confusing when you start to think about how much you need. This guide is mainly for the people that are complete neophytes to this subject; if that's you, I hope it helped.
But remember that if you're ever confused about anything, Everest is an excellent tool, and the people in the forums here are always friendly and willing to help out.
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