A Buyer’s Guide to PC Memory
PullQuote 166If there’s one thing that most desktop computers and laptop computers can do with, it’s more memory (often called RAM). No matter how much you have, it’s never quite enough. Newer computers come loaded with 512 MB or 1 GB of memory. That’s OK for basic work, but if you’re doing anything with graphics, gaming, or running Windows Vista, then you’ll definitely need more memory. And if you have a slightly older computer, then a little extra RAM goes a long way.
Luckily, the price of RAM has dropped noticeably over the last couple of years. In fact, it can be more cost-effective to buy extra RAM than it is to buy a new computer. The problem is, though, how to get the correct memory for your PC. This TechTip offers a few suggestions.
Note: This TechTip only looks at memory for PCs that run Windows. Throughout the TechTip, the terms memory and RAM are used interchangeably. For some memory rudiments, see our
TT 37 – “Memory Basics”.
Types of RAM
This TechTip assumes that you have a PC that was made within the last three to five years. Most desktop and laptop computers of that vintage use DDR memory. DDR stands for double data rate. DDR memory offers twice the data transfer rate of the previous generation of memory.
Of course, all DDR memory isn’t created equal. There’s DDR, DDR-2, and DDR-3 memory. DDR is the oldest of the group. So old, in computer terms anyway, that it is being phased out. DDR-2 is about twice as fast as conventional DDR memory. DDR-3 is, again, about twice as fast as DDR-2. However, to achieve the higher speed for the RAM, the latency of the memory suffered. Latency is the amount of time, in CPU cycles, that your computer takes to get to data that’s in memory. At lower CPU speeds, DDR-3 is somewhat slower than DDR-2. At higher speeds, though, DDR-3 is noticeably faster.
Another difference between the different types of DDR memory is the number of pins each has. Pins are what connect the memory to the motherboard in memory slots. DDR memory has 184 pins, while DDR-2 and DDR-3 memory have 240 pins. While the pins in DDR-2 and DDR-3 memory are the same size, they are incompatible.
When you’re looking at DDR memory, you’ll read information like DDR-266 PC-2100. All that refers to is the amount and rate of data that the RAM can transfer. So, in DDR-266, the 266 refers to the theoretical number of data transfers per second — in this case, 266 million. PC-2100 refers to the type of memory module. The 2100 also refers to the peak rate of data transfer that the memory supports — in this case, 2,100 megabits per second. The higher the number, the higher the number of data transfers per second, and the greater the peak transfer rate.
Like a computer’s CPU, memory also has a clock speed. The clock speed of the memory is measured in megahertz (MHz) and is the actual speed at which data is transferred to and from memory. The clock speed of RAM is usually half the number of data transfers per second that the memory module is capable of. So, with DDR-333 memory, the clock speed is 166 MHz. So, why is the number double with DDR RAM? Because data is transferred to memory twice.
This may seem like superfluous information, but it will come in handy when you go to upgrade your RAM.
- The first steps that you should take when choosing RAM are to find out:
- How much memory your computer has
- The maximum amount of memory that it supports
- What type of memory your computer uses
How much memory you’re packing
To find out how much memory your computer packs, right click on the My Computer icon on your desktop and then click Properties to open the System Properties dialog box. The amount of memory in you computer is listed in the bottom right corner of the dialog box.
The maximum amount your PC can handle
Unfortunately, this doesn’t tell you how many sticks of memory your computer contains. You can only be sure of this in a couple of ways. If, for example, your computer has 512 MB of RAM, then it most likely has one stick of memory installed. Any higher amount and you need to open the computer’s case and take a look. If you have 1 GB of memory and there are two sticks of memory installed, then each will weigh in at 512 MB.
Depending on the vintage of your computer, it probably supports a maximum of anywhere from two to four GB of RAM. You can find out how much memory your computer supports, as well as the types of memory it can handle, at the Web site of memory maker Crucial. You can get information in two ways. The first way is to click the Scan My System button on the main page of their site. You’ll be taken to the Crucial System Scanner page, where you can allow Crucial to collect information about your system.
If you’re uncomfortable with doing that, or if the scan doesn’t work for some reason, or if you’re looking for information about another computer, then use the Crucial Memory Advisor tool on the main page of the site. All you need to do is select your computer’s manufacturer, select the make of computer, and then select the specific model. Once you’ve done that, click the Find It button. You’ll get very detailed information about your system and its memory.
So, what happens if the Crucial Web site turns up nothing? If your computer came with a manual — printed or electronic — for the motherboard, you can probably find information about your PCs memory in there. If you’ve lost the manual or didn’t get one, check the Web site of your PC’s manufacturer for information. That’s where your favourite search engine comes in handy. When I wanted to upgrade the memory on one of my ThinkPads last year, I did a Google search for ThinkPad 40 specifications. I found the information I was looking for at the Lenovo Web site.
Finally, your last resort is to pop open your PC case and physically check the memory. Most RAM modules have a sticker on them that gives you the important information about the memory: type, speed, and amount.
Mixing and matching RAM
There was a time when you had to have the same memory in your PC — you couldn’t, say, match an 8 MB module with a 4 MB one. It wouldn’t take; instead of 12 MB your computer would only recognize the 8 MB module. Thankfully, those days are over. You can now mix and match. For example, two of my laptops pack a 1 GB stick of RAM and a 512 MB stick of RAM.
A problem may arise, though, if you try to mix and match different speeds of RAM. The different RAM just might not be compatible. On the other hand, some memory is backwards compatible. Remember my ThinkPad? According to the Lenovo Web site, it supports PC-2100 memory. When I went to upgrade it, I couldn’t find the right memory. Actually, my business partner snapped up the last 1 GB stick of PC-2100 RAM for his ThinkPad before I could get my hands on it. At another store, though, a technician told me that I could use PC-2700 memory with my existing PC-2100 memory. It just wouldn’t work at the higher data transfer rate. In the year or so since the upgrade, I’ve had not trouble with the memory.
That said, you can’t mix DDR memory with DDR-2 or DDR-3. Even if your motherboard supports two types of memory, you can generally only use one type or the other.
Buying your RAM
Like any consumer, you want the best quality for the best price. There are a number of memory manufacturers out there, and their wares vary in quality. Of course, it’s usually best to choose a well-known brand. The ones I usually recommend are:
Memory_IMPatriot and A Data aren’t too bad, as is OCZ. The key advantages to those three manufacturers is that their memory is somewhat cheaper than the others that I mentioned. Check your favourite bricks-and-mortar retailer, or drop by Geeks.com.
Installing the memory
The actual process of installing your new memory is outside of the scope of this TechTip. If you want detailed information, watch this video at HowStuffWorks Videos.
After a little research, you’ll find that upgrading your computer’s memory isn’t as daunting a task as it seems. By doing it yourself, you’ll not only get a sense of geeky satisfaction but you’ll also save yourself some money.