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Using a Thumb Drive to Install Windows 7

Date: February 3, 2010
Author(s): Robert Tanner

Microsoft may be selling Windows 7 exclusively on DVD’s, but did you realize that it takes very little effort to create a bootable thumb drive and install from that? We’re taking a look at two popular methods of accomplishing this, and as you’ll see, it couldn’t be easier to install Microsoft’s latest OS onto a PC with no DVD-ROM. It’s faster, too!


Gone are the days where a floppy drive is needed. In the extraordinarily rare event some device’s firmware (such as a graphics card BIOS) requires an update, it is possible to mimic the floppy drive entirely without ever having to install one. In short, a program that creates a virtual floppy drive and some quick, creative formatting of any USB flash drive can turn it into a convenient “floppy disk” with the requisite 1.44MB capacity limitations.

For this article we are going to keep it simple and show how easy it is to take a Windows 7 DVD (or an already ready ISO file) and image it to a 4GB or larger USB storage device. This USB device can literally be anything with a minimum of 4GB capacity that plugs into the USB port and is detected by the computer’s BIOS as a drive. MicroSD, SDHC, flash drives, USB hard drives, just about any will work! That said, for the sake of performance and ease, we do recommend high-capacity USB flash drives for the best results. If the USB storage is too slow, it will increase the time required for the OS to install.

Why might someone be interested in doing this, you ask? Convenience and speed are two big factors here. While Windows 7 already installs in not quite half the time required by Windows XP, it can actually be faster. What may surprise many enthusiasts to learn is that the DVD drive has become the bottleneck on a moderate and especially higher-end performance system.

Techgage's Windows 7 Desktop for SSD Testing

Out of personal curiosity I recently installed Windows 7 using two different SATA-based DVD drives (a Sony and a Lite-On) and the install times were around twelve minutes each. On the other hand, when using a regular 16GB USB flash drive, the time taken from the HDD configuration screen to reach the finished desktop was only a little over seven minutes! Switching to a USB flash drive saved almost five minutes off the already amazingly short install time!

For anyone that must regularly install Windows 7 on computers, this can quickly become a time saver, and for those that have that older computer in the back room or servers that lack optical drives, this provides yet another option. Floppy and CD drives have almost been completely exorcised from today’s systems, and regular DVD drives are starting to show their age.

Kingston Thumb Drives

There are plenty of students who have ordered the special discounted version of Windows 7 online, yet all they receive are a few files and an .exe to run inside Windows. Some quick Googling will turn up several ways to convert these files to an ISO image.

Whether you are a student, a network administrator, classroom teacher, computer enthusiast, or simply someone that’s come to the abrupt realization they are out of spare DVDs, there are plenty of reasons to have a spare USB flash drive with Windows 7 on it laying around. Let’s not forget that the Windows 7 installation media also doubles as a bootable last-ditch recovery disc!

Before we begin, lets note that USB 2.0 is limited to 35MB/s throughput as a best case scenario. Most memory cards tend to fall around 20MB/s, but flash drives are almost random. Any flash drive bought today has the potential to max out the USB bus, yet there are still some that won’t be any better than 15-20MB/s. A DVD drive offers a best case of approximately 21MB/s, so we recommend using any USB flash drive or memory card that can do the same or better. A quick check with any free disk utility such as HD Tune will let you know.

Using the Windows 7 USB/DVD Download Tool

Now as that’s over with, let’s get started. If you don’t have the Windows 7 USB/DVD tool then it can be downloaded from here. Simply install the small tool and launch it. You will be greeted with the below screen, so simply point the program to the ISO file.

Windows 7 USB/DVD Download Tool

If you already have the Windows 7 DVD but wish to make an ISO of it for this task, we recommend the free trial of MagicISO. While our favorite tool ImgBurn would be our first choice, it does not appear able to correctly image the Windows 7 installation disc.

Next, choose if you wish to use the tool to burn your ISO to a DVD or image it to a USB device.

Windows 7 USB/DVD Download Tool

Now carefully select the correct drive, as you wouldn’t want to erase the wrong USB flash drive or hard drive! This process re-formats the USB device, so make sure it is completely empty and all files have been copied elsewhere before you proceed.

Windows 7 USB/DVD Download Tool

Please note that if the Windows 7 USB program says the Windows 7 ISO is not valid, then the program used to create the ISO file from the DVD either isn’t able to correctly image the disc or the file that was selected is partially corrupt. Most Windows 7 x64 ISOs should be around 3GB in size, while the x86 version will hover closer to 2.3GB.

Now you have it, that’s all it takes to convert any USB flash drive into a Windows 7 installation disk! It’s so easy, even a cave man could do it. Your device should now look like this:

Windows 7 USB/DVD Download Tool

Windows 7 Folder Layout

Of course there is one last important thing left to do, and that is to configure the BIOS to boot to your USB device! Leave the device plugged in when you reboot. Some BIOS’s differ but generally the setting needed can be found under the Advanced BIOS Features menu. Look for the “First boot device” and change it to USB-HDD. Alternatively if the computer offers a quick-boot menu, pressing F8 on ASUS, F10 on Intel, and F12 on Gigabyte motherboards during the POST’ing process will bring it up.

Most users will need to perform a second step. At the main BIOS screen go to the “Integrated Peripherals” menu and look for a setting labeled “USB Storage Device”. This setting should be enabled if present as it tells the BIOS to look for USB devices during the POST process.

Any computer that is recent enough to run Windows 7 or was made within the last several years should be capable of booting to a USB device, so if you have followed this guide and are still having don’t hesitate to ask for help in our forums!

Using Diskpart

If for some reason Microsoft’s tool doesn’t work as you planned, or you simply prefer to do things the command-line way, we’re going to cover an alternative option, diskpart. There’s yet another option that involves using a tool called bootsect, but due to potential issue of using a 64-bit ISO on a 32-bit operating system, we will stick to using the second, and preferred method.

First, you will need the Windows 7 ISO file. Second, you will need either WinRAR, 7-Zip, or another utility that can extract ISO files. Either program will allow you to right-click and extract the ISO’s contents.

Open the Start Menu and type ‘cmd’ into the search box, without quotes. Once it’s shown in the results, either hold Shift and click the cmd link, or right-click and select “Run as administrator”. Either way, you will want an Administrator-level command prompt. Once here, with the command prompt open and your USB drive plugged in, type “diskpart” sans quotes and wait a few seconds for it to poll the USB devices.

Make careful note of which disk number belongs to the USB flash drive or device you wish to use, as we are sure that you really would not wish to find out you just wiped out your entire C: drive or backup drive’s contents! Below, disk 3 is the 4GB flash drive we want to use.

Using Diskpart to Install Windows 7

Next, type the following commands in order without quotes, hitting enter after each one:

select disk #
create partition primary
select partition 1
format fs=ntfs

Of course, the # in the ‘select disk #’ represents the actual number of the disk, which in our case was 3. What clean does is completely removes all of the existing data and partitions, while active activates the partition, and assign creates it a drive letter.

Using Diskpart to Install Windows 7

Windows 7 Folder Layout

Now the only thing left to do is copy all the files over from the extracted Windows 7 ISO. Navigate back to the extracted files as shown above, and then either CTRL+A or use the mouse to select all folders & files and drag them over to your USB device. Presto, you’re done and ready to boot to your install disk!

All thumb drives are a bit different, and some are a little more complicated to deal with than others. If for some reason you try either of our steps here, and still can’t get your drive to boot, please feel free to post in our related forum thread below and we’ll help you out. Also, while we didn’t delve into the bootsect method in our guide here, 2Tired2Tango from our forums did, so I recommend reading his guide as well if neither of these two techniques above work.

Good luck, and happy installing!

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