Heatspreaders

IMHO, they are about as useful as colorful “Brembo” brake covers. In other words, they are not really useful and won't help much. Generally, a waste of money if you have to pay for them. So, why do so many associate heatspreaders with high-performance?

Well, heatspreaders are a way for memory manufacturers to dress up their expensive, high-performance modules and make them look more impressive. This allows them to charge a higher price premium. Without heatspreaders, anyone would be hard-pressed to differentiate a high-performance module from a standard module. So, don't judge any memory module by its heatspreader. That would be like judging a car's performance by its body kit.

PCB

Many assume the PCB (Printed Circuit Board) to be nothing more than a board on which you stick those memory chips on. Well, when it comes to RAM, the quality and design of the PCB greatly affects the memory module's performance. How?

Explaining it could take a lifetime, so I'll condense it with some references thrown in for extra oomph. The PCB has wires that deliver data transmitted in the form of electrical peaks and valleys. However, if there is sufficient distance between one wire and another wire, the capacitance of the circuit can create crosstalk which is the signal in one wire interfering with the signal of another wire. Good PCBs can mitigate this and increase performance by maintaining signal integrity.

Also important is signal routing on PCBs. Good PCBs route the signals away from areas of potential interference. They also take the shortest path. Why is this important? According to the Johnson Nyquist law and the law of simple resistance/Ohms power law, part of any signal will be converted into both heat (Ohm) and noise (Nyquist). Good PCBs therefore keep the paths as short as possible by proper routing and keeping the resistance as low as possible.

Good PCBs also minimize interference by other means, with the simplest way to combat noise and crosstalk as well as RFI/EMI issues being the placement of signals between an enlarged ground plane and the supply plane. It is easier to do this using PCBs with more layers than those with fewer layers as the number of layers limits routing options.

Also important is the control of reflection, which is what happens when a signal reaches a point of infinite impedance and cannot go forward. The signal then reflects in the opposite direction, which as you can imagine isn't a good thing for the signal behind it. Good PCBs provide termination, or end points with enough resistance to turn the ending signal into heat. It's very much like how 10BASE-T networks with end terminators work.

Well, there's not much I can tell you about selecting PCBs because I haven't done much research on consumer modules lately. However, I do know that memory modules bearing the BGUXXXX mark are high-quality PCBs from a Taiwanese company called Brainpower. Such PCBs can actually give you a 10% boost in clock speed when you overclock.

Warranty

Like everything in life, memory modules do and will die, so never get caught with your pants down. Memory manufacturers will give you at least a year's warranty, but the better ones will give you a lifetime warranty. But keep in mind that their definition of “lifetime” may not be what you think it is.

Therefore, there are no hard and fast rules here, except you should always read the warranty conditions before you buy the module, so you are at least aware of your rights. While on the point of warranties, here are a few points I'd like to go through.

1. Most of the time, it is the distributor (not the manufacturer) that will handle the warranty claim, so make sure the dealer you buy from has a good reputation and isn't selling you parallel imported modules which will not be covered by the local warranty.
    
2. Buy from a dealer close to you. After all, you have to send the module to them, or pay for the delivery. A shorter distance would definitely cut down on your cost.
    
3. A dealer with an automated RMA system will always save you a lot of hassle, so choose one that uses such a system.