Everything you need to know about upgrading your RAM

Everything you need to know about upgrading your RAM

Many PC owners won't necessarily need to ever update their RAM. But if one day you decide to, you might understandably make the assumption that adding faster and larger amounts of memory will allow your games and other applications to run faster.

However, perhaps surprisingly, that's not always the case. And that's exactly what we're looking in to here.

The memory landscape

Computer memory is divided into two main types: DDR3 and DDR4. The former is older, having debuted back in 2007, while the latter only hit the mainstream recently, with Intel's X99 platform in 2014.

They both work using the same principle: flash chips store data that the computer needs immediately, but it's lost when it's no longer useful or your PC is turned off.

It's governed by several common attributes: larger amounts mean more data can be stored, and higher MHz ratings mean memory runs at a faster speed, so data moves in and out quicker.

Different locations of the key notch (on the insertion edge of each DIMM) prevents a DDR3 (top) or DDR4 stick (bottom) from being installed into an incompatible board or platform

The newer standard, DDR4, has several advantages over DDR3. It runs at a higher frequency, so it's able to process your tasks at a faster rate. DDR3 is generally clocked between 1,333MHz and 2,400MHz, while DDR4 ranges from 2,400MHz to 3,200MHz.

It's possible to blur these lines with overclocking (forcing the processor to go at a faster speed), but, for the most part, DDR4 is faster. It balances those better speeds with chips have double the internal memory banks, faster burst access and higher data transfer rates.

DDR3 and DDR4 memory work with different motherboards and chipsets. Essentially, DDR3 is compatible with almost every motherboard and socket out there, but DDR4 is only compatible with boards using Intel's X99 chipset and LGA 2011 processor socket.

DDR4, however, does have a downside – increased latency (the time it might take to perform a task). Newer DDR4 2,133MHz memory has a latency rating of CL15, which means it'll take 14.06ns to perform a read, while DDR3 1,600MHz memory reads at 13.75ns.

That's a tiny margin, and DDR4 negates this disadvantage with its generally higher clock speeds. Nevertheless, if you'd like to keep an eye out, look for CAS ratings. This indicates latency, and lower is better. No matter which memory you buy, you'll have to deal with channels.

Dual-and quad-channel setups are the most popular and improve performance by allowing motherboards to use multiple channels to send and receive data simultaneously, therefore improving bandwidth. It's possible to run memory in single-channel mode, but there'll be a performance decrease if you run a single stick of memory rather than two or four.

The changing PC landscape

The variety of different specifications means that prices vary wildly. The cheapest 16GB DDR3 kits made from two 8GB sticks currently cost about £65 ($90, AU$130), but the most expensive can cost more than £200 ($279, AU$400).

It's a similar story with DDR4, which dual- and quad-channel kits also vary by huge amounts when it comes to price.

But these will always be more expensive than their DDR3 equivalents. Manufacturers claim that the increased speeds and better features provided by pricier memory will make a dramatic difference to performance. But we're not so sure, so we've set up some test rigs to try and find out just how much memory you really need.

Both of the test rigs we've set up use MSI motherboards. One uses Intel's Z79 chipset with a Core i7-4770K processor, while the other is an X99 PC with a Core i7-5820K chip. Both use operating systems installed on a Samsung 850 Evo SSD, and both use an Nvidia GeForce GTX 980 graphics card.

We've already mentioned the different processors and chipsets that work with DDR3 and DDR4, but there's more to choosing your components than just making sure your new gear is compatible on paper. Intel's Haswell architecture is behind the bulk of its current desktop processors, and it was its first to include native support for dual-channel memory, with up to 32GB of RAM.

It's used for chips that range from cheap Celerons and Pentiums to expensive Core i5s and i7s, and these desktop Haswell chips all plug in to the LGA1150 socket. The LGA 1151 socket is also DDR4-compatible.

Most Haswell-based processors are deployed with mobos that have Intel's H87, Z97 and Z87 chipsets. When it comes to memory support, they're all impressive. They handle four slots that accommodate two sets of dual-channel memory, and most full-size ATX boards also support 32GB or 64GB of memory at rapid speeds.

The X99 chipset introduced DDR4 to the (high-end) mainstream market, bringing with it faster clock speeds and better power efficiency, but with increased latency

Support for faster memory

Intel has further developed its CPU architecture with Haswell-E. Processors that use this system also use the LGA2011 socket and X99 chipset, which means that support for DDR4 is included – and so, in turn, that means integrated support for faster quad-channel memory when compared to DDR3.

AMD's processors and APUs, meanwhile, use the Piledriver architecture. Its own memory controller was given a speed boost over the previous generation of AMD hardware, but memory support ultimately still isn't as good on this side of the fence. All of AMD's current chips support DDR3 memory, however, some of them are restricted to 1,600MHz or 1,866MHz memory, while only a handful top out at 2,133MHz.

Like Intel, these boards do support dual-channel memory. Processors and chipsets aren't the only bits of your PC that need to be checked before shelling out for new memory – motherboards are also vital. You'll need to make sure a board has the right number of slots.

You'll also need to check what amount and speed of memory it can accept: it's no good dropping a few hundred bucks on a 32GB 3,000MHz kit if your motherboard only goes to 16GB and 2,666MHz.

There are nuances to be examined, then, but for the most part, the memory landscape is heartening. No matter what processor, chipset or motherboard you use, you'll be able to equip a PC with plenty of high-end memory at decent speeds. That's good for anyone wanting to upgrade parts of their PC, but it's not necessarily great news for companies that rely on flogging expensive, high-end kits.

Future developments from Intel and AMD will only improve the situation. Intel's latest architecture, Skylake, will support DDR4 across all of its full-fat desktop chips, but it'll also be backward-compatible with DDR3, which adds a huge amount of versatility. We also expect to see improvements to the memory controller and support for larger amounts of memory running at faster speeds.

AMD isn't standing still, either. Its next proper desktop architecture is called Zen, and it'll offer full DDR4 support to bring the company's chips alongside Intel.

The first set of DDR3 benchmarks we locked and loaded were PCMark 8's Home, Creative, and Work tests – a trio of suites that simulate the kind of low-intensity tasks that take place on many systems, from web browsing and video chatting to word processing and spreadsheets.

BENCHMARK RESULT

Our first tests deployed the bare minimum of sluggish DDR3: 8GB of RAM clocked to 1,333MHz. With this RAM, the PC returned scores of 5,170, 6,794, and 5,234 points, in the Home, Creative and Work tests, respectively.

However, with 8GB of 1,600MHz memory deployed, the scores barely improved, with the Creative run only jumping to 6,852. There wasn't even much of a difference in these tests when we installed 16GB of 1,866MHz memory: in those three benchmarks, the machine scored 5,270, 6,961, and 2,525.

The biggest leap came in the Creative test, which suggests more memory helps with photo editing and other trickier tasks, but it's hardly a game-changing jump in performance.

Whether you've got DDR3 or DDR4, upping the size or speed of your memory makes little difference to BioShock Infinite

We saw similarly modest gains in other photo-related applications. GigaPan Stitch knits together a group of high-resolution photos, and our test image took four minutes and 12 seconds to complete in a PC with 8GB of 1,333MHz memory.

That only improved by 11 seconds when we doubled the RAM and upped its speed to 1,866MHz.

Modest impacts

Other application benchmarks we did saw similarly modest impacts. A Cinebench R15 CPU test with two 4GB, 1,600MHz sticks returned a result of 703 – doubling the memory and improving its speed to 1,866MHz only improved that figure to 751.

We only saw big improvements in a few benchmarks when running DDR3 tests. In PCMark Vantage, our 8GB 1,600MHz PC scored 18,313 points. But doubling the memory and running it at 1,866MHz saw that result jump by almost 3,000 points - a significant increase.

Indeed, our theoretical tests indicate that improving memory amounts and speeds does make a difference, but that these performance gains don't generally translate to real-world tests.

In SiSoft Sandra's multithreaded bandwidth test, our 2x 4GB 1,333MHz setup scored 16.57GB/s, but doubling the memory and improving its speed to 1,866MHz saw that result jump to 23.33GB/s. There was a decent jump in single-threaded bandwidth, and we also found cache bandwidth also improved significantly when faster memory was added in larger amounts.

The leap from dual-channel to quad-channel memory doesn't often have much of an impact on our application tests, either. In Cinebench R15's OpenGL test, a machine with two 4GB 1,600MHz sticks scored 111 frames per second, with this score only jumping to 117fps with four 4GB 1,600MHz sticks installed.

When running applications using DDR3, then, the differences between slow and fast memory often aren't huge – and, as long as you've got 8GB of memory installed, then you're going to have enough to get most stuff done in real-world situations.

There was a noticeable performance difference between our PC with 1,333MHz and 1,600MHz memory installed. But once beyond that 1,600MHz speed, the gaps between different memory speeds narrowed rapidly. We ran GeekBench single-core benchmark on 1,600MHz memory, and then again at 2,800MHz memory, but its result only improved by around 100 points.

The benchmarks demonstrate that there are performance gains to be had by installing more memory at faster speeds, but those gains are only noticeable in high-end applications. For most of us, 8GB or 16GB of 1,866MHz memory will be more than enough for our purposes.

RAM AND PC GAMING

We tested a variety of games using our DDR3 rig, but only found sporadic improvements. In Metro: Last Light, a machine with two 4GB 1,333MHz sticks averaged 126fps, but improving to a pair of 8GB 1,866MHz DIMMs saw that result jump to 144fps.

In both BioShock Infinite and Batman: Arkham Origins, though, the improvements were far less impressive – a few frames better in the minimum frame rate benchmark, and only a gain of 2fps to the average rate.

There also wasn't much of a difference in any of our Unigine Heaven 4.0 tests. In all of our DDR3 tests – ranging from a system with two 4GB 1,333MHz sticks to a machine with four 8GB 1,600MHz DIMMs – the benchmark's average frame rate hovered between 63.4fps and 66.8fps.

Metro: Last Light was our only DDR3 gaming test to noticeably improve with more memory

Those configurations didn't differ much in 3D Mark's Fire Strike test either: in the same range of memory setups, our results only jumped between 11,607 points and 11,635 points.

The DDR4 difference

Newer DDR4 memory operates with faster speeds, better channel support, and Intel's latest chipset and controller, so we expected our tests to reveal bigger performance disparities.

Our initial tests, though, appeared to follow the blueprint already set out by the older DDR3 sticks. In the Cinebench R15 CPU test, a machine with two 4GB 2,400MHz sticks scored 1,143 points. Doubling the memory and increasing its speed to 3,000MHz, however, only saw that result jump to 1,190.

The X264 video-encoding test led to similar patterns. Our more modest PC ran through its two tests at 205 frames per second and 68 frames per second, but increasing the memory's speed to 3,300MHz saw those results only inch forward to 211fps and 73fps – that's hardly a jump up that will make a big real-world difference for the user.

GigaPan Stitch's photo-editing tool only saw a couple of seconds' worth of improvement with its memory sped up, while Geekbench exhibited similarly small gains. Our first DDR4 PC scored 22,165 points, but doubling the memory to 8GB, running at 2,666MHz, only saw the score jump to 22,849.

Multithread bandwidth

It's a shame because, as with DDR3, theoretical tests illustrated that improving speeds and amounts did make a difference. When we had two 4GB 2,400MHz sticks installed, our test PC delivered 15GB/s and 28.58GB/s of single- and multithread bandwidth, with those numbers jumping to 17GB/s and 32GB/s with those same sticks clocked to 3,300MHz.

Those same benchmarks illustrated how DDR4 copes with quad-channel larger amounts of memory. Our machine with two 8GB sticks may have delivered 32GB/s of multithreaded bandwidth, but doubling the memory saw that figure leap to 45GB/s then, but those figures weren't always translated to real-world tests.

So, we'd say that it's not a vital addition to your PC, unless you're keen on buying a Haswell-E system to run intensive work applications or the most demanding games.

One of the motherboards we used to carry out our benchmarks

DDR4 and gaming

We saw a big jump in just one of our gaming benchmarks, Metro: Last Light, while testing with DDR3. However, updated DDR4 memory proved even less dramatic. Improving the amount and speed of memory saw our Metro: Last Light results jump by a mere couple of frames, and our biggest improvements in BioShock Infinite and Batman also only saw increases of a frame or two, no matter the amount or speed of DDR4.

We'll let Unigine Heaven have the last word. Our PC averaged 62.7fps with two 4GB 2,400MHz sticks installed, but this only improved to 64.2fps once we installed four 8GB 2,666MHz DIMMs.

There's no doubt about the pure, naked speed of DDR4, but it looks like we're at the point, for gaming especially, where any 8GB dual- or quad-channel configuration will be ample. Memory isn't the bottleneck in gaming. Processors and graphics cards are more likely to be holding back your frame rates.

If you are ever putting together a new setup it might be tempting to buy the fastest and largest memory kit you can afford. But as many of our benchmarks illustrate, aiming for the top of the tech tree is actually an unnecessary extravagance when it comes to memory.

Larger and faster?

The story is the same whether you're creating a PC to use DDR3 or DDR4. A decent amount like 8GB or 16GB running at a reasonable speed will be enough to handle most tasks you throw its way, whether it's for work or gaming.

You'll still see benefits if you buy larger and faster kits, sure, but they'll be less significant – so, it's only worth looking toward these kits if you're a true enthusiast who wants the best parts available or if you're running unusually demanding software and need to wring every last bit of performance from your PC.

Quad-channel kits, meanwhile, are great if you're using applications that'll truly take advantage of DDR4's improved architecture, such as encoding or rendering, but most people won't feel the benefit. It's no surprise, then, that it's only available with expensive X99-based CPUs.

The majority of PC users, even enthusiasts, just don't need to cough up for the priciest kits around, and that's definitely no bad thing. Memory, processor and chipset developments have levelled the playing field, which means it's one less component to worry about if you're putting together a PC.

source: .techradar