AHCI or IDE - which is better? Description of the mode, characteristics

It is quite natural that owners of desktop computing systems and laptops tend to increase their productivity in one way or another. To solve this problem, some use the so-called overclocking (overclocking) of components, others - the introduction of settings through the opportunities provided by the developers. When choosing any method, it is important to understand what exactly is required to obtain, and to understand well the features of the chosen method.

"Bottleneck"

It is known that one of the slowest components of a modern computer system is a hard disk based on a classical spindle system. Today there are SSD-analogues, but they have not yet received a mass distribution because of too high a cost. Therefore, conventional HDDs are installed on almost every computer. As a result, it turns out that DDR3 memory easily transfers 20,000 MB / s; The internal bus of the central processor allows to process ten times more data; And a hard drive with the SATA-3 standard only in ideal conditions "accelerates" to the present 100 megabytes per second. It is no accident that we recommend using at least some powerful SSD models for system files. From all of the above, a simple conclusion follows: it is the HDD that slows down the modern system, being thus the "bottle neck". And since the user can easily make changes to the way the disk subsystem's commands are handled, to some extent affecting the speed, one often hears the question of which mode is better: AHCI or IDE.

Standards

The interaction of the disk with the rest of the components of the computer system occurs through a special control controller. This chip serves as a kind of translator for the teams, a converter. Until recently, the only "language" that the controller could understand was the IDE protocol. It arose at the dawn of the computer industry and was upgraded several times. With the advent of high-speed SATA-drives, a radical redesign of the protocol was required. So AHCI arose. Advanced Host Controller Interface easily copes with the increased data flow (interface), supports the fashionable queue of NCQ commands and implements the ability to disconnect the device "on the move." So, what is AHCI? IDE, which added some new features. So everything is simple, at first glance.

Opportunities and prospects

Since the standards are backward compatible (the SATA device works perfectly with the IDE protocol), there is almost always an item in the BIOS or its analog that allows you to select the desired mode. In many cases, only thanks to this it is possible to achieve the normal working capacity of the computer. The mode selection function is only present in the software of those motherboards that provide for work with SATA. These are all modern systems. However, here you can also attribute hybrid solutions that allow you to connect both classic IDE devices (PATA, wide connector comb) and SATA (compact connector). So, AHCI or IDE? What's better? To make it easier to understand this, we will list the "bonuses" that the user receives by activating a more modern mode:

1. The speed of data transmission via internal electronic circuits "controller of the disk - controller of the board" reaches from 1.5 Gb / s (gigabit) for the modification of SATA-1 to 6 in the third revision. Recall that UDMA-6, which can work with old hard drives, provides only 133 Mbps.

2. Talking about what is better - AHCI or IDE, you can not fail to indicate support for NCQ technology. Its essence lies in the fact that the hard drive can "intervene" in the queue of the stream of commands, rebuilding them to improve the efficiency of the work.

3. The ability to "hot" replace the device, which does not require disabling the entire system.

4. Parallel access to all disks at once, without using sequential switching.

This is a very tempting list of possibilities. It is not surprising that the question: "AHCI or IDE: what is better?" Is, perhaps, one of the most painful. Many computer owners, surprisingly, still believe in the "magic button".

Theory and practice

So after all, AHCI or IDE - which is better? From the above list, we can conclude that the obsolete protocol significantly loses to the new one. However, this is not quite true. Let us consider this point in more detail. Yes, indeed, the data transfer rate has increased tens of times, but the magnetic disks in the drives have rotated at a speed of 7200 revolutions (the most popular solution) and are rotating. Accordingly, in the process of reading, no revolutionary breakthroughs occurred. In no HDD test user will see 6 Gbps of transmission. Even 200 Mbit is unattainable! The exception is solid state drives. If there is such a device in the system, you can not understand the question: "AHCI or IDE: what is better?", But immediately activate the updated protocol. However, as we pointed out, because of the cost of such drives have not yet become massive.

Very often in debates about what is better - AHCI or IDE, the main argument in favor of the first is the ability of the protocol to support NCQ. Indeed, when several programs are actively accessing the hard disk, this function allows you to rebuild the flow of requests in the most optimal way. However, in an average computer to a disk, more than two or three programs are rarely accessed at the same time, so it is impossible to talk about the total absence of acceleration, but it is obtained within the error margin.

IDE or AHCI - which is better? Windows 7, when the last mode is activated, supports the connection / disconnection of the SATA device "on the move". Quite convenient, especially in server systems, where shutdown is undesirable. However, for the use of "hot swapping" it is recommended to use not internal connectors, but the SATA modifications introduced on the case.

And, finally, the protocol allows several drives on the bus to work simultaneously, rather than waiting for requests. It is in this case that the potential of NCQ is fully disclosed. For the average computer is not relevant.

In the end, it turns out that although the protocol AHCI, from the point of view of technology, is more interesting, nevertheless from its inclusion the bulk of users will receive nothing but moral satisfaction. There are only two exceptions to the general rule: the server system and the use of SSD.

Nuances of use

Although you can switch modes in BIOS in a few seconds, one important point should be considered. It consists in the following: if the operating system has been installed, for example, with AHCI, then after transfer to the IDE the download may not be possible. This is not the rule, but more often than not everything happens just like this. Therefore, before installing the distribution you need to decide with which protocol the disk subsystem is scheduled to work. Packages of AHCI drivers began to be integrated into the system only with Vista. All previous solutions from Microsoft have no built-in support, so you either need to use "builds", or prepare the media with the appropriate driver before installing. With the new standard, Windows 7 works fine. Switching SATA from IDE mode to AHCI should be done from the BIOS (the Configure SATA item). In very rare cases, you may need to make changes to the registry.

Switching method

In order to get into the BIOS, right after turning on the computer system, you need to press the Delete button (personal computers) or F2 (laptops) several times in a row. Depending on the implementation, the desired item can be in any sections. For example, to activate it, you may need to translate Boot Mode into CSM instead of UEFI, then the Compatible (IDE) and AHCI appear in the SATA Controller . The desired item can be found in the SATA Enhanced section. You need to carefully review the entire existing list. After switching, press ESC and agree to save the changes.

Results

The decision on which protocol to give preference depends on several factors. First of all, from the operating system used. From compatibility on the "iron" level. And of course from the load on the subsystem. The higher it is, the more preferable AHCI is. If you analyze all the reviews, you can say that both protocols work fine, with the correct configuration without causing any glitches. Nevertheless, it is more appropriate to use the updated version. This, so to speak, hurt "for the future", for example, to buy SSD.