大多数人不会花很多时间考虑RAM。毕竟它不像CPU或GPU那样性感。(GPU)在大多数情况下，任何人都关心的是它是否足以满足他们的需求。然而，事实是RAM远不止是纯容量。
内存技术的改进是计算机性能如此出色的关键部分。世界上最快的 CPU 只能以蜗牛的速度工作，如果它是由缓慢的、过时的RAM提供的数据。在撰写本文时，在构建或购买计算机时需要应对 三种类型的RAM 。
有DDR3，它已有十多年的历史，但仍然存在于今天使用的大量计算机中。然后是DDR4，这是新计算机的当前标准。DDR5尚未在您可以购买的计算机中找到，但该标准已于 2020 年年中正式发布。
这意味着不久之后实际的DDR5硬件开始出货。那么，这几代RAM(RAM)有什么区别，哪一款最适合您今天选择呢？
什么是 DDR？
在我们深入探讨不同DDR(DDRs)之间的代际差异之前，有必要首先解释一下“DDR”是什么。这不是Dance Dance Revolution，以防万一那是您立即想到的地方。并不是说我们对此一无所知！
不，DDR 是Double Data Rate的缩写，是指这种内存技术用于在其时钟周期的高峰和低谷执行操作的特殊方法。换句话说，以 100Mhz 运行的DDR内存芯片与以 200Mhz 运行的SDR（单数据速率(Single Data Rate)）芯片执行相同数量的操作。
这就是为什么DDR内存速度是以模块实际时钟速度的两倍写入的原因。例如，DDR3 1600 RAM实际上以 800Mhz 运行。
带宽差异
不同代DDR之间的主要区别之一是它们提供的带宽量。每一代都提供了数据传输率的显着提升。当然，您可以购买接近DDR4低端的高端DDR3 ， DDR5也可能如此。
在产品范围的边缘肯定会有一些性能重叠。但是，除非您的目标是以最低的价格构建系统，否则每一代新一代都应该比上一代快得多。
增加的带宽有多大的不同？
一般来说，拥有大量较慢的RAM比拥有少量的快速RAM更好。然而，在NVME SSD(NVME SSDs)和多核 CPU时代(cores)，它变得比以往任何时候都更加重要。
在给定CPU支持的(CPU)DDR代中，带宽差异不太重要，但重要的是使用多通道内存。换句话说，如果您的主板支持双（或更多）通道内存，请确保您在正确的插槽中拥有正确数量的模块以启用它。
能量消耗
随着每一代RAM的出现，性能都会提高，功耗会下降。这在考虑移动计算机时特别有用，但在任何情况下，更少的功耗和更好的性能都不是一件坏事。
虽然RAM不是迄今为止最耗电的组件，但结合其他组件的节能，这一切都导致现代系统的能源需求大幅下降。
归根结底，DDR3系统可能会在您的电池或电费账单上更加困难，因为设计用于该代DDR的组件将在其时代消耗更多电力。
预取缓冲区大小
预取缓冲区是RAM中的一块区域，在将数据移交给CPU之前会在其中加载数据。最初的DDR标准可以获取一个数据单元，但DDR一次可以做两倍的数据。DDR3和DDR4可以同时处理 8 个单元，而DDR5可以达到 16 个，具体取决于具体型号。
预取缓冲区越大，RAM的效率就越高。这是因为如果缓冲区更大，则缓冲区包含CPU下一步需要的数据的可能性更大。
DDR3、DDR4和一些DDR5模块都具有 8 个单位的缓冲区大小。因此，就效率而言，没有什么可以将它们分开。具有 16 单元缓冲区大小的DDR5(DDR5)内存在纸面上代表了一个巨大的飞跃，但对于大多数用户来说，它是否是现实世界计算中值得注意的升级仍不清楚。
物理差异
通过精心设计，不同代的DDR具有不同的硬件外形。它们都以DIMM（双列直插式内存模块）(DIMM (Dual Inline Memory Module))的形式出现，但连接器边缘的槽口位于不同的位置。
这使得不可能将内存插入错误的插槽。这将特别成问题，因为旧的DDR标准比新技术使用的电压要高得多。噗！
什么是 LPDDR？
您可以在超极本和其他需要通过电池供电长时间运行的设备中找到 一种DDR 。
低功耗 DDR (LPDDR)(Low Power DDR (LPDDR))最初是DDR1的修改版本，但从那时起，作为移动(DDR1)DDR的基础类型越来越分化。因此，不要将LPDDR 3,4和 5 视为其桌面同名的移动版本。相反，它们是具有大量自身独特DNA的高能效存储技术。
延迟问题
您可能听说DDR 4的延迟比DDR3更长。也就是说，DDR4需要更长的时间来响应读取和写入其存储单元的请求。这在纸上是正确的，但在现实生活中没有明显的区别。DDR4在其他方面要快得多，因此总体上仍优于其前身。DDR 5可能会改善延迟问题，但即使没有，它也会在整体上胜过DDR 4 。
哪个 DDR 最好？
这个问题并不是那么容易回答，因为它取决于你的起始位置：
- 如果您在本文发布时正在购买或构建新计算机，那么DDR4是您的最佳选择。
- 如果您有一台运行DDR3的计算机，那么只有在达到CPU和GPU的限制时才考虑升级。DDR4本身并不足以成为转向新系统的充分理由。
- DDR5在一段时间内仍将保持昂贵且缺乏支持，因此值得等待支持它的主流主板和处理器再跳槽。
然后是内存带宽与容量的问题。如前所述，对于大多数用户来说，使用速度较慢的RAM比使用速度较慢的RAM更好。(RAM)话虽这么说，你应该得到你能负担得起的最快的内存，以满足你需要的容量。在不需要它的系统中 放置过多的RAM对性能没有任何帮助。(RAM)
因此，额外的RAM将被闲置并浪费金钱。例如，大多数游戏系统将使用 16GB 的RAM，因此放入 32GB 将提供递减收益。最好的策略是确定最适合您需求的 RAM 总量(total amount of RAM)，然后获得您能负担得起的该RAM大小的最快版本。
DDR3 vs DDR4 vs DDR5 RAM: Which Is The Best?
Most people don’t spend a lot of time thіnking about RAM. It’s not as sexy as the CPU or GPU after all. For the most part, all anyone cares about is that there’s enough of it for their needs. However, the truth is that there’s much more to RAM than pure capacity.
Improvements in memory technology are a key part of why computer performance is so good. The fastest CPU in the world can only work at a snail’s pace if it’s being fed data by slow, obsolete RAM. At the time of writing, there are three types of RAM to contend with when building or buying a computer.
There’s DDR3, which is well over a decade old but still present in plenty of computers in use today. Then there’s DDR4, which is the current standard for new computers. DDR5 isn’t yet to be found in a computer you can buy, but the standard was officially released in mid-2020.
Which means it won’t be long until actual DDR5 hardware starts to ship. So, what’s the difference between these generations of RAM and which one is best for you to choose today?
What Is DDR?
Before we dive into the generational differences between the different DDRs, it’s worth explaining what “DDR” is in the first place. It’s not Dance Dance Revolution, in case that’s where your mind immediately went. Not that we’d know anything about that!
No, DDR is short for Double Data Rate and refers to the special method that this memory technology uses to perform an operation at both the peak and the trough of its clock cycle. In other words, a DDR memory chip running at 100Mhz does the same number of operations as an SDR (Single Data Rate) chip running at 200Mhz.
This is why the DDR memory speeds are written at twice the actual clock speed of the module. For example, DDR3 1600 RAM actually runs at 800Mhz.
Bandwidth Differences
One of the key differences between the different generations of DDR is the amount of bandwidth they offer. Each successive generation has offered a significant jump in data transfer rates. Of course, you can buy high-end DDR3 that comes close to the lower end of DDR4 and the same will likely be true for DDR5.
There’s bound to be some performance overlap at the edges of the product spectrum. However, unless you’re aiming to build a system for the lowest price, each new generation should be significantly faster than the last.
How much of a difference does increased bandwidth make?
In general it’s better to have a higher amount of slower RAM than a smaller amount of fast RAM. However, in the age of NVME SSDs and CPUs with many cores, it’s becoming more important than ever.
Within the DDR generation that a given CPU supports, bandwidth differences are less important, but what does matter is making use of multi-channel memory. In other words, if your motherboard supports dual (or more) channel memory, make sure you have the right number of modules in the right slots to enable it.
Power Consumption
With every new generation of RAM, performance goes up and power consumption goes down. This is especially beneficial when considering mobile computers, but less power consumption with better performance is never a bad thing in any context.
While RAM isn’t the most power-hungry component by far, combined with power savings in other components it all adds up to a big drop in energy needs for modern systems.
The bottom line is that a DDR3 system is likely to be harder on your battery or electricity bill, because components designed to work with that generation of DDR will consume more power by virtue of their era.
Prefetch Buffer Sizes
The prefetch buffer is an area of RAM where data is loaded before being handed over to the CPU. The original DDR standard could fetch one unit of data, but DDR could do twice as much at a time. DDR3 and DDR4 can do an impressive eight units at once and DDR5 can go up to 16, depending on the specific model.
The bigger the prefetch buffer is, the more efficient the RAM is. This is because there’s a larger chance that the buffer contains the data that the CPU needs next if it’s bigger.
DDR3, DDR4 and some DDR5 modules all have a buffer size of eight units. So there’s nothing to separate them in terms of efficiency. DDR5 memory with a 16-unit buffer size represents a huge leap on paper, but it’s still not clear if it’s a noteworthy upgrade in real-world computing for most users.
Physical Differences
By deliberate design, different generations of DDR have different hardware form factors. They all come in the form of a DIMM (Dual Inline Memory Module), but the notches on the connector edge are in a different place.
This makes it impossible to slot memory into the wrong slot. That would be especially problematic since older DDR standards use so much more voltage than the newer technologies. Poof!
What’s LPDDR?
There’s a type of DDR you’ll find in ultrabooks and other devices that need to run for long periods of time from battery power.
Low Power DDR (LPDDR) was initially a modified version of DDR1, but since then has diverged more and more as a ground-up type of mobile DDR. So don’t think of LPDDR 3,4 and 5 as mobile versions of their desktop namesakes. Instead, they are aggressively power-efficient memory technologies with a significant amount of their own unique DNA.
Latency Issues
You may have heard that DDR 4 has more latency than DDR3. That is, it takes DDR4 longer to respond to requests to read and write from and to its memory cells. This is true on paper, but makes no perceptible difference in real life. DDR4 is so much faster in other respects that it still outperforms its predecessor overall. DDR 5 may improve on the latency issue, but even if it doesn’t, it will also outperform DDR 4 as a whole.
Which DDR Is Best?
This question isn’t all that straightforward to answer, because it depends on your starting position:
- If you’re buying or building a new computer as of this article’s publication, then DDR4 is the way to go.
- If you have a computer running DDR3, then only consider upgrading if you reach the limits of your CPU and GPU. DDR4 by itself is not a good enough reason to move on to a new system.
- DDR5 will remain expensive and poorly-supported for some time, so it’s worth waiting for mainstream motherboards and processors that support it before jumping ship.
Then there’s the issue of memory bandwidth versus capacity. For most users it’s better to have more slower RAM than less faster RAM, as mentioned before. That being said, you should get the fastest memory you can afford for the capacity you need. Putting too much RAM in a system that doesn’t need it will do nothing for performance.
That extra RAM will therefore go unused and be a waste of money. For example, most gaming systems will do with 16GB of RAM, so putting in 32GB will offer diminishing returns. The best strategy is to determine what total amount of RAM is best for your needs and then get the fastest version of that RAM size you can afford.
