Understanding RAM for the Smart Shopper: A Guide
You may be coming here after looking at the new iMac that’s coming out at the end of the year because it is more expensive than it should be. Many people who are new to building computers are usually under the impression that more RAM is better, which is generally true but it all comes down to your wants and needs. We’re going to try and break down any assumptions that you might have as well as give you information on things you might find useful in your venture for a custom computer.
Let’s define terms associated to RAM so that when you’re looking into it you know how it should look and how it should operate. The first thing to note is that RAM or Random Access Memory works as the short-term memory of computers. RAM also works as the middle man between the storage and CPU (or brain) of any computer. The more RAM as in 4GB, 8GB, etc., you have the more things you’ll be able to access at the same time. When people talk about RAM they are usually referring to a particular type of RAM called SDRAM which stands for Synchronous Dynamic RAM not to be confused with SRAM or Static Dynamic RAM which you don’t need to worry about. There are a few types of sizes referred to as DIMM (or dual in line memory module) which are in desktops and servers as opposed to SO-DIMM (or small outline dual in-line memory module) which usually appears in smaller devices. DDR or double data rate means two transfers in the ram happen per clock cycle.
DDR3 vs DDR4
Although DDR3 came out in 2007 and DDR4 came out in 2011 DDR4 has taken its time to take over the market. The difference between DDR1, DDR2, DDR3, and DDR4 is not obvious if you look at their physical appearance because they all fit into each other’s slots, the only difference would be that you wouldn’t be able to boot from mixing them up. You can’t buy DDR3 RAM to put in a motherboard that is meant for DDR4 without it wanting to catch on fire. If you’re like me you would want a modern motherboard which would probably ask for DDR4 memory now so why buy a motherboard that requires DDR3? Well it might just be slightly more affordable but I would only buy DDR3 RAM sticks for an upgrade but not for a brand new system. DDR4 has made improvements since its previous generation in now ridiculous frequencies, latencies, capacities, and power consumption. People who are looking to make a new computer from scratch should consider a DDR4 compatible motherboard with matching memory sticks to stay open to upgradability down the line without having to overspend for a DDR3 stick that is no longer manufactured.
Dual Channel vs Quad Channel Configurations
Dual memory channel gives us two dedicated high through-put data channels whereas quad memory channels give us four of the same data channels. The idea behind multiple channels versus bigger capacity RAM sticks is to get a higher bandwidth with two sticks of memory instead of one stick of memory. Your computer will be faster if you add more channels to it making quad channel superior in theory. Your motherboard either has dual or quad channels and it’s only a matter of looking at the colors of your RAM channels. If you find four channels to be one color it is usually the manufacture’s way of letting you know the best way to configure ram. It might be dual or two memory sticks and it might be three or four.
Crucial to the performance of your RAM is the CAS (or Column Access Strobe) latency which is the amount of time in nanoseconds that it takes for your RAM to respond to a request from the CPU. You can find this small number on a stick of your RAM. The number will appear with a few others in a pattern such as 7-7-7-21. The CAS latency number is the first. This number matters because it is the first thing that needs to happen in order for the rest to happen. You might think that the lower the number means you’ll have a faster response time but you’ll find a lack of visible performance. To find the total latency or delay in performance of your ram you have to take the CAS latency and multiply it by the frequency which will give you the real-world delay.
Frequency or Speed
When looking at RAM for sale one of the biggest pitches is the clock speed which look similar if not the same as 1600MHz, 1866MHz, and in some cases even come as 4000MHz. Higher clock speeds are assumed to give performance of gods but the truth is that the frequency of the clock speed is at the mercy of the CAS latency. If you have a low CAS latency as discussed earlier, you will not benefit much more than if you had a higher CAS latency. The higher numbers are actually only slightly visible in enthusiast grade motherboards and CPUs as they are at the bleeding edge of technology and mostly unstable. Heck, most motherboards won’t allow speeds higher than 24000MHz. In the end, most people end up choosing capacity over speed because you’ll be able to do more with 16GB than you would be able to with8 GB.
I hope this guide helps you look out for what matters in RAM as you consider literally thousands of options. My recommendation for anyone who cares about computers would be to buy at least 8GB of RAM even though there are smaller options because you will ultimately be shortening the life of your PC if it’s always choking on the lack of RAM. I would also suggest that you look at what you’re trying to do with your computer and see if you need more or less RAM. Although it’s tempting to buy into the higher clock speeds advertised for DDR4, it would not be difficult to live with lower clock speeds.