Buying memory can be quite confusing, especially when you plan on overclocking. Shoes breaks down all the numbers so you understand what to look for.

Out of all the components you have to select for your computer, purchasing memory is arguably the most confusing. Capacity, Speed, CAS Latency, Timings, Voltage, ECC… Enough to make even the most knowledgeable gamer less than excited about choosing memory for their new build. I know for sure that most of the questions I have had to answer since the launch of this site have been about memory speeds and the like. Well, rest assured, GotFrag Hardware has got you covered.

A lot of this information has been covered in bits and pieces in our previous articles, but here you will find it all nicely put together. So then, let’s start out with the basics shall we?

RAM
Random Access Memory. All computers have RAM. As far as gaming goes, it is a member of the big three in terms of performance influence (Video card, CPU, RAM). Plan on loading games up fast? Plan on having anything running in the background of your games? Yes? Then choosing the right amount and kind of RAM is very important.

So what exactly is RAM? RAM is a form of temporary storage in your computer. Just like a human’s short-term memory, it doesn’t take a lot of time or thought to pull up information that is stored there. When your CPU calls for information from your hard drive, it is first transferred to the memory, where is will be able to be fed to the CPU at much faster rates than if it were coming directly from the disk itself. To illustrate how the whole thing works, let’s see what happens to the memory when you push the power button on your computer:

For more information about how RAM works, click here.
For more information about how Hard Drives work, click here.
For more information about how CPU’s work, click here.

Capacity
Quite simply, the amount of information your RAM can store. The more RAM you have, the more information your CPU can access at very fast speeds, and the more responsive your system will feel. So, with more RAM comes higher speed. Well kind of, the caveat is that there is definitely a point where having a lot of extra RAM is not going to make any kind of positive difference at all. Unless you are a power user, meaning you use multiple programs that each require large amounts of system resources, you probably don’t have use for over 1GB (1024MB) of RAM (yet). In the future, we will probably see operating systems, not to mention games, using up a great deal more RAM than they currently do, so 2GB (2048MB) of RAM may not be a bad idea for those looking to future proof.

Speed
Definitely the stupidest naming scheme of them all. Whoever decided on these labels should be shot. I mean, they have like 3 different numbers that all mean the same thing? What gives? But I digress, each label actually does add its own little piece of information about the specs of the RAM. So let’s take a look at each one and what they mean:
(note: using the permanent fixture on Newegg’s “Top 5 Sellers”, Corsair Value Select, as an example)

PC 3200
I’m actually not sure what the “PC” means in this case, but the “3200” is how RAM manufacturers are telling you the transfer rates of your memory, in this case 3200MB/s. That’s a lot of information. That’s a lot a lot of information.

DDR 400
DDR stands for Double Data Rate. There is really nothing special about this. Basically all system RAM you see today will have DDR in the product description. It simply means that there are 2 transfers of data per clock cycle.

200 MHz
For all intents and purposes, this is really the most important number to consider when buying RAM. It is the actual operating frequency of the RAM. The other numbers are dependent on this number, not the other way around. It is also very important when it comes to overclocking, which will be discussed later.

How they all go together
Starting with 200 MHz. Each clock cycle consists of 2 data transfers, so in double data rate RAM, the effective clock speed of the RAM will be 200 MHz times 2, which is 400 MHz (DDR 400). From there, each transfer consists of 8 bytes of data, so 400MHz times 8 bytes is 3200MB/s (PC 3200).

Now on to the more advanced part
{mospagebreak heading=The Basics&title=Timings and CAS Latency}
Timings and CAS Latency
CAS latency is one of the timings that you see in descriptions of RAM, so it will be addressed in the same manner as will the other timing numbers: briefly. The lower the of CAS latency the better. In fact in general, latency is a bad thing to have, you always want to avoid it. If your RAM has a CAS latency of 2, then it will be ever so slightly faster than RAM with a CAS latency of 3, assuming both are running at the same clock speed. The difference is quite small in most real world applications, but if you want to get the most out of your computer’s memory, make sure it has a low CAS latency. For a more detailed look about how RAM works and what these timing numbers mean, check out ZeGermans’ RAM discussion article.

Voltage
The amount of voltage your RAM can take is largely dependent on what type of RAM it is. The word “type” in the previous sentence has a dual meaning. The type of RAM you have could be DDR, or quite a few of you probably have what is called DDR2, the second generation of DDR memory. The differences between these two, understandably from the opening sentence, is mainly voltage. DDR2 RAM can operate at 1.8 Volts as opposed to 2.6 Volts on DDR for the same frequencies. This has some pretty massive implications in terms of both power consumption and overclocking, which for now we are not going to worry about. The other “type” of RAM you could have depends on what it says on the little DRAM chips on your RAM stick. The little white letters on each black chip on a RAM DIMM indicate from what company the chip was produced and what kind of chip it is. These little letters could read something like on the picture on the left, where the chip manufacturer is Samsung, and the kind of chip is TCCD.

TCCD? BH-5? 5B-G? …?
For most casual computer users and even for most gamers, these little descriptions might as well not even be there, they are not important in the least. But for a select few gamers and any serious overclocker, they are terms to live by, they might even be the single most

important factor in determining the success of your overclock. How can that be? They are just letters and numbers! Well, each of them mean something different. When semiconductor manufacturers like Samsung, Micron, Infineon, Hynix, or Winbond produce a chip, they have different characteristics. They have different voltage tolerances, different physical constructions, different appearances, etc. Interestingly, over the years of DDR’s reign, these little differences alone have been some of the most scrutinized by the overclockers of the world. This chip will clock to these speeds at this voltage, this chip will clock to those speeds at this other voltage – it’s all quite well documented and understood amongst the overclocking enthusiasts.

So what does this mean to you? Well, knowing the differences between all these terms will put you on the best grounds to determine for yourself what any given stick of RAM will be capable of when being overclocked. Most of the RAM related questions I get are usually about overclocking – Will this RAM allow me to overclock my (insert processor here) to 5 billion GHz?

Right then, on with the descriptions. The gross majority of enthusiast RAM on the market today are utilizing one of these 5 chips (or a close variant thereof): Samsung TCCD, Micron 5B-G, Micron 5B-D, Winbond UTT CH-5, Winbond UTT BH-5.

Samsung TCCD
This chip from Samsung is usually a dream for overclockers. The defining characteristic of a TCCD memory chip is its ability to reach tremendous clock speeds at relatively low voltages. Many people have reached up top ~300 MHz on TCCD at only 3.0V, which is the max voltage you would want to use for TCCD anyway. The advantages of the low voltage is low heat output. With other RAM chips, at high speeds the voltage is also high, causing for a high heat output which calls for active cooling. There is no active cooling needed for TCCD chips. The only real disadvantage of TCCD is that it is unable to maintain tight timings at high clocks. If you are running at 250 MHz for instance, you will probably have to had loosen up the timings to something like 2.5-3-3-8 instead of 2-2-2-6 at stock 200 MHz. Variants of TCCD usually have TC in common, TCC5 for example.

Micron 5B-G
Crucial is the poster child for Micron. One of the things that continues to draw people to Crucial’s BallistiX series is their continued use of Micron chips, which are traditionally of very high quality. 5B-G kind of shares some of the characteristics of TCCD, in that it can reach a decent clock speed without having to bump the voltage much at all. It runs stock at 2.8V, but will run with tight timings and everything at 2.6V, and can reach up to around 250MHz at around 2.65V. That is really good considering your heat output will hardly be greater than stock. Timings will also be pretty decent at this level, you don’t have to loosen them very much at all. However, 5B-G seems to hit a wall at around this voltage, and increasing it all the way up to its max of 3.6V will hardly do anything above giving you an extra 30 MHz and heavy temperature increases throughout your system. The max overclock for these kind of chips is around 280 MHz, and even at 250 MHz they offer a very nice overclock with a very little voltage increase – good stuff.

Micron 5B-D
Micron’s 5B-D chips are very similar to the 5B-G chips in the sense that the stock voltages and max voltages are the same. However, 5B-D differs from 5B-G because you can get a higher max clock out of them. Also, 5B-D is generally unable to run at tight timings at higher clocks, and usually requires around 3.0-3.1V to achieve its maximum clock speed which is right around 300 MHz.
{mospagebreak title=Chips, Recommendations}
Winbond UTT CH-5
The claim to fame of the Winbond chips is their ability to maintain very tight timings at high clocks. However, these chips are strongly not recommended for people that do not intend on overclocking their RAM. Those of you looking to have some fast memory at stock speeds should look elsewhere. Sure, the CH-5 will be fast at stock, but it needs very high voltage at stock to be as fast as TCCD is at stock on low volts. For instance, look at the OCZ VX series of RAM, which uses exclusively Winbond CH-5. The stock voltage on those chips is 3.3V. Nevertheless, CH-5’s ability to reach fairly high clock speeds at insanely tight timings is very appealing to heavy overclockers (especially AMD overclockers), and is probably the main reason you can rarely find it for sale.

Winbond UTT BH-5
Ahh, the elusive and sought after BH-5. When Winbond released this chip after its BH-6, overclockers everywhere soon found it to be pretty much the most scalable chip yet. Then they found out that it could reach 3.6V without significant performance loss, at which point everyone went nuts. The problem with it was that Winbond left the memory chip IC market shortly after the release of CH-5 and stopped production short on BH-4 which is, as far as anyone knows for sure, a mythical chip with supposed overclocking characteristics that combine the best characteristics of BH-5 and TCCD. The difference between BH-5 and CH-5 is that BH-5 can reach significantly higher clock speeds, rumors have that people have reached well above 320 MHz, however it requires a bit more voltage to do so. And again, simlar to the CH-5, BH-5 can maintain very tight timings at these high clock speeds. BH-5 also has tight timings at stock clock speeds using less voltage than CH-5. For the most hardcore overclockers, there is no better choice than BH-5, if you can find it of course.

Overclocking
Some points about overclocking RAM that may or may not be obvious:

PC 4000 runs at PC 3200. No DDR motherboard will allow you to pop in a 250 MHz RAM stick and have it operating at that speed right off the bat. This is because the stock FSB for all processors right now is at 200 MHz. When you overclock, you can reach that 250 MHz quite often, but before overclocking, that PC 4000 memory you bought will not be running at its optimal speed. That said, the only disadvantage of getting memory rated higher than PC 3200 is the price. Other than that, there is not a “guarantee” that the memory will run with as tight timings as PC 3200 at 200 MHz, but that is not necessarily a disadvantage, depending on how you look at it. The advantages of buying memory rated above PC 3200 are that you will not have to worry about overclocking to 250 MHz or maintaining certain timings at that speed. Memory rated at PC 4000 WILL operate at 250 MHz with the advertised timings. Below that it will work, above that it will work, but there is no guarantee about the timings. PC 3200 (if it is enthusiast RAM) usually will operate at 250 MHz, but with no guarantee on the timings (dependent on RAM chip). Below that it will work, above that it might work, but the only guarantee on the timings is on the low end.

Recommendations
What would this article be without recommendations? Here are the actual products that carry the aforementioned chips:

Samsung TCCD
G.SKILL Extreme Series PC 3200 2 x 512MB
Price: $151.82 (USD)
Stock Voltage: 2.7
Timings: 2-2-2-5

Micron 5B-G
Crucial Ballistix PC 3200 2 x 512MB
Price: $119.00
Stock Voltage: 2.8
Timings: 2-2-2-6

Micron 5B-D
Crucial Ballistix Tracer PC 4000 512MB
Price: $86.00
Stock Voltage: 2.8
Timings: 2.5-4-4-8

Winbond UTT CH-5
Mushkin Redline PC 4000 512MB
Price: $121.95
Stock Voltage: 3.3
Timings: 2-2-2-6

Winbond UTT BH-5
G.SKILL F1 PC 3200 2 x 512MB
Price: $139.50
Stock Voltage: 2.7
Timings: 2-2-2-5

Credits
Micron - Micron Technology Inc.
Samsung - SAMSUNG Semiconductor
G.Skill - DDR Series
Crucial - Crucial BallistiX
Mushkin - XP4000

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