The difference between brand-name RAM and commodity RAM. I’ve been seeing a lot of questions along the lines of, “Do I really have to buy name-brand memory when I can find memory for half the price on PriceWatch?” on message boards lately. I talked about memory some in Memory-buying secrets, but I didn’t really go into the difference between generic/commodity/broker memory and the expensive stuff.
There are three factors that go into the quality of a memory module: the quality of the chips, the quality of the printed circuit board (PCB), and manufacturing.
When memory chips are made, they are tested. A memory chip that runs at or below spec gets classified as an A-grade chip. Chips with minor defects are classified as C-grade chips and shouldn’t be used in PCs.
Memory manufacturers will also charge varying amounts based on how much testing they do for the chips. Top-tier chips are guaranteed to have a failure rate of .1% or less–we’re talking one in a thousand chips failing here.
The least expensive chips aren’t tested at all.
The only way to ensure you’re getting these best-of-the-best chips is to buy name-brand memory. The best way to ensure you’re getting C-grade or untested chips is to buy the cheapest module you can find.
Inexpensive PCBs use a four-layer design, with signal layers on the outside, and power and ground sandwiched inside. This is inexpensive to produce and easy to repair. Unfortunately, this design leaves you open to signal noise, which can corrupt the data stored in the chip, and lead to unpleasant things like BSODs.
A better approach is to put the signal layers inside, and put power and ground on the outside, protecting them. Better still is a six-layer design, which adds two more ground layers for even better isolation. The higher the memory speed, the more important this extra isolation becomes.
You can sometimes tell the difference between a 4-layer and a 6-layer board by looking at it under a strong light. By turning it slowly, you can isolate discrete layers with the naked eye. However, it’s impossible to tell the difference between power, ground, and signal layers with the naked eye.
Name-brand vendors use high-quality PCBs. Some even proudly proclaim it when they use 6-layer boards. Again, the best way to get a poorly designed 4-layer board is to buy the cheapest memory you can find.
The third factor is assembly. When soldering chips to PCBs, things can go wrong. Trust me. I’m very good at demonstrating. While no one puts together memory modules by hand (I hope), my plumber-like soldering skills make me appreciate good equipment. Quality solder joints are bright and shiny, and they’re applied very quickly. Intermittent solder joints cause problems, and they’re maddening.
Kingston puts every module through rigorous testing. Other name-brand manufacturers test as well. When you don’t even know who made your module, it’s impossible to know whether it’s had the proper testing. Putting it in a PC and watching the BIOS check is not proper testing. Memory has to be very far gone to fail that test.
Frequently vendors will advertise Micron memory or NEC memory. A Micron or NEC stamp on the chips doesn’t necessarily mean they manufactured the module! Be sure to find out who assembled the module–they usually stamp the PCB, or they put a sticker on the module itself. If you find a so-called Micron module on Pricewatch for half the price that Crucial is asking (Crucial is a division of Micron), chances are it’s a no-name module that just happens to have Micron chips on it.
So, does it really make a difference?
As an IT professional by day, I work on a large network–roughly 700 PCs. I’ll conservatively estimate that farm of PCs has 1,000 memory modules collectively. We buy name-brand memory (Crucial, Kingston, Viking or Simple) exclusively. We buy PCs from Micron, so they have Crucial modules in them. Macintoshes generally come with Crucial or IBM modules.
A typical memory module has 8 chips on it, and it only takes one bad chip to make the whole module bad. I’ve seen two bad memory modules cross my desk–so we’re talking two bad chips out of a batch of 8,000. So if you’re buying a single module for a home PC, your chances of getting a lemon are pretty slim if you get a good name brand.
For my own use, I buy name-brand memory modules. Usually this means Crucial; I got a great deal over the summer on some PNY memory so I bought a couple of sticks. I use high-quality memory, I don’t overclock, and I generally don’t run experimental software. I almost never get a BSOD or an illegal operation error, even when running Windows 95 or 98. I reboot my Windows 9x boxes about once a month on average, and half the time that’s because I installed or uninstalled something and it requires me to reboot. To give you an idea how I use PCs, at the moment I have seven applications running, with 11 windows open between them, and two TSRs running. That’s my idea of moderate use.
I’d rather have 64 megs of Crucial memory than a gig of the cheap stuff. Hopefully now you see why.