 Hello everybody! This video will show you how to enable AHCI mode for a computer where an operating system had already been installed. The SATA interface can operate in two modes – ADE and AHCI. IDE – a compatibility mode for all your equipment and software. In effect, in this mode, SATA capacity is no different from its predecessor – ATTA or PATTA interface. AHCI – a new mode for memory devices where a computer can use all SATA advantages, primarily higher speed of data exchange with SSD and HDD, as well as hot-swapping of hard disks. When you activate AHCI mode, it increases the speed of access to files in memory devices and improves overall performance of your computer. It is quite possible that AHCI mode is already enabled in your PC. It can be checked in several ways. 1. Go to Device Manager. Open the section IDE – ATTA – a TAPI Controllers. If there is a device containing AHCI in its name, as in our case, it means that AHCI mode is used in this computer. 2. Go to BIOS or UFI. Watch another video on our channel to see how to enter BIOS or UFI in your PC or laptop. Find the link in the description. Find an item with the name, storage options, SATA mode, SATA emulation or anything similar. If the value of such item is AHCI, then AHCI mode is already enabled. If the value says IDE, don't hurry to change it into AHCI. The matter is that if you just enable AHCI mode for after-windows installation, you will face Absort Error – inaccessible boot device, which is known as Blue Screen of Death. Or your system will refuse to boot, getting stuck in a series of stunts. That is why it is recommended to enable AHCI before installing Windows. Please take note that in some computers there is no BIOS option to change to AHCI mode. In this case, the problem can sometimes be fixed by updating the BIOS. Watch one of the videos in our channel to learn how to update BIOS. Find the link in the description. There are several ways to enable AHCI mode for SATA on a computer where Windows is already installed, and Windows will work normally after this operation. 1. Register Editor To do it, press Windows Plus R and type in the command regedit. Go to the section HKEY LOCAL MACHINE, SYSTEM, CURRENT CONTROL SET, SERVICES I A STORE V. Double-click on START ELEMENT and set its value to zero. In the next section, I A STORE A V, START OVERRIDE, set the zero value for the element zero. In the section STORE AHCI, set the value to zero for START ELEMENT. In the subsection START OVERRIDE, set the zero value for the element zero. In our case, there is nothing to see, but you will see it if AHCI has not been enabled yet. After that, close the register editor, restart the computer and go to UFI or BIOS. For the first time after the restart, it is better to boot Windows in SAVE mode. All methods to boot Windows in SAVE mode are described in detail in this video by our channel. You will find the link in the description. In UFI or BIOS, find SATA settings to select the mode for memory devices. Switch them to AHCI, save settings and restart the computer. After the restart, Windows will start installation of SATA drivers, and when it is over, it will ask you for another restart. Do it, and AHCI mode in Windows will be enabled. If the first method didn't work for some reason, here is another way to do it. To begin with, if you have problems with booting Windows in AHCI mode, go back to IDE and restart the computer. After that, launch the command prompt as administrator. Tap in the command prompt, bcd edit, set, current, save boot minimal and press Enter. After you see a message that the operation is successful, restart the computer. Before booting your PC, enable AHCI in BIOS or UFI using the method we have already described and save the settings. The computer will boot in SAVE mode and install all necessary drivers. Launch the command prompt as administrator again and type in bcd edit, delete value, current, save boot. After the command is executed, restart the computer again. This time Windows should boot with AHCI enabled and without any problems. As you can see, these actions can theoretically result in unwanted consequences such as inability to start the operating system. That is why you should do it only if you know why you do it. If you can end the BIOS or UFI and if you are ready to fix unforeseen consequences if anything happens, for example, you may have to reinstall Windows in AHCI mode. If you liked this video, click the like button below and subscribe to our channel to see more. We'll be glad to answer any questions and comments. Thank you for watching and good luck.