You probably know that doing a clean install gives you a fresh start and a clean slate. That may sound nice, but when you think about the time and energy you’ll sink into getting everything back to the way you like it, it’s pretty tempting to upgrade in place. Even more tempting, every modern operating system—like Windows 10 or OS X Yosemite (and soon, El Capitan)—make it so easy: Just download an installer, run it, get some lunch, and when you’re back you have the latest and greatest, without having to do anything.
What you might not know is there are a host of other benefits to doing a clean install, that make it worth considering. Beyond just giving yourself a fresh new OS to play with, here are a few other things you’ll get when you take the time to start from scratch.

You’ll Rid Yourself of Quirks, Bugs, and All Those Problems You Could Never Pin Down

I actually hate doing clean installs, but I love clean systems. On one of my laptops (a Macbook Pro,) I’ve never performed a clean install, ever. When it was new, I migrated directly from the machine it replaced. As new versions of OS X came out, I upgraded in place. Things went smoothly enough I just never bothered. However, as you use a computer—especially over several years—you’ll get some quirks. Maybe nothing serious, but certain bugs and quibbles that you know your computer does that you just can’t pin down and fix. Maybe it’s slowness when you do a specific thing, so you learn to not do that thing. Maybe some app crashes all the time, so you find an alternative. You spend some time researching those quirks, and find out that either no one has the same problem or lots of people do and they all have dozens of different solutions, none of which seem to work for you.
You can probably tell where this is going. A clean install will kill those bugs for you, almost completely. If there’s something specific to an program, you probably can’t get around that. But if it’s something strange about how your computer behaves, or how a program you use interacts with the OS, you probably already know in the back of your mind that a clean install will fix it. I knew, for years, and I still didn’t do it. I just assumed that the hassle and effort of doing a clean install on that system and getting everything up to speed again just wasn’t worth it. In reality, the actual productive time I lost trying to fix this Macbook Pro’s myriad wake-from-sleep problems, USB quirks, and multi-display issues was far more than the afternoon it took to wipe the drive, reinstall Yosemite, and reinstall the applications I actually used.
A good clean install also gives you peace of mind. Ever use a Windows machine and get worried you may have installed something at some point that’s not so above board, or that you may have had your security compromised at one point or another? Security software or no, there’s a reason why technology professionals blow away systems completely and reinstall if they think they’re compromised. They don’t waste time diagnosing it or running tons of antimalware tools. It’s just faster and safer to start over and restore data from known, good backups. If you’ve ever worried the same about your desktop, well, nuke it from orbit. It’s the only way to be sure.

You Get a Performance Boost Without Having to Clean Everything By Hand

Look, we’ve mentioned before that you actually don’t need to reinstall Windows regularly to keep your system performing in tip top shape, and that’s absolutely true. However, there’s only so much you can do tby running CCleaner , removing programs you don’t need, and cleaning out the apps that run automatically on startup. Those things are great to do on a regular basis, but over time the cruft that comes with regularly using your computer, cleaning it, and using it some more accumulates to the point where it’s tough to decide what to keep and what to remove. The key here is “regularly.” When a new OS launches, that’s when you should think about doing a clean install.



The great thing about a clean install is that you don’t need to sit at your computer for hours and research every service, every poorly named process, or every unfamiliar application sitting in the Task Manager. You don’t have to disable services and reboot your computer to see if they’re actually necessary for something you use, or some holdover from an old version of whatever. Just take the stress and blow it all away along with that ancient, cluttered mess of an operating system. You can start from zero, building back up slowly based on the things you actually use, not the things you installed once and used for a while.
Of course, with all of this comes a performance boost, and a pretty significant one at that. Windows 8 and Windows 10 largely boot faster than their predecessors, and run faster too, even on moderate systems, but they can only really do so without the baggage of previous versions, old and outdated apps and drivers, and a shorter list of startup items. Once you clear them all out and replace them only with the things you actually need, you’ll see a huge improvement. Similarly, if you’ve upgraded to Windows 8 or Windows 10 and thought “this isn’t as fast as I’ve read it was,” the problem isn’t that everyone was lying to you: It’s probably your system. Clean it out.

You’ll Clear Out Bloatware, Old Leftover Junk Files, and Recover a Ton of Disk Space

If your computer is an OEM you bought off the shelf, it’s probably brimming with crapware and bloatware. Hell, if it’s a Windows 10 upgrade from Windows 7 or 8, it probably comes with a bunch of apps you might not want. We’ve talked about how to get rid of them before after the fact, but you’ll notice option three in that piece is the one we’re talking about here: Going nuclear and just reinstalling your operating system. In Windows, clearing out all that crap will save you precious system resources and disk space. While Macs generally don’t come with a lot of bloatware (although Apple includes enough of its own stuff you may not want that we certainly could call it bloatware) cleaning that out returns much needed disk space—and more disk space can mean a performance improvement, especially in OS X, which notoriously loves to keep cruft around from old operating systems after in-place upgrades, even if it’s no longer needed.



As an example, as I’ve been testing the El Capitan public beta, I wound up getting kernel panics trying to install the most recent updates. I couldn’t figure out why, but if I downgraded everything was fine. After researching, I learned Apple’s shiny new OS didn’t care for some ancient extension files from an old version of VirtualBox of all things, files that should have been automatically cleaned up ages ago. Of course, they never did, and caused problems years down the line.
Keeping all of that crap off of your computer (or better yet not letting any of it on in the first place) will keep your system running in great shape, and makes sure that every time you look at task manager or activity monitor to see what’s eating up all your memory, you’ll know at least it’s something you installed, and not some crap someone’s trying to shove down your throat.



It’s the Closest You’ll Get to that “New Computer” Feeling Without Building a New Rig

Those of you who build your own computers, or just like to do clean installs when you get a brand new one so you can truly start from scratch understand that “new computer” feeling. That feeling of infinite possibility, where everything is snappy and fast, your system is lean and trim, running efficiently, and ready for whatever you demand of it. Well, it may go without saying, but doing a clean install is the closest you’ll get to that feeling without actually building or buying a new PC. And it’s a great feeling, too.
Sure, you have to go through installing all of your programs, migrating your data, and setting everything back up the way you like again. You may even have to restore files from backups. It’s all worth it. Seriously, and it doesn’t even have to be as difficult as you might think it is. When I used to work in IT, I used to be able to crank out tons of clean installs on new computers every day, as long as I had the space and time to do it. That included installing the operating system, installing all of the user’s necessary apps, and even migrating their settings, setting up accounts and email, even getting their desktop to look the way it did when they gave me their old computer to be replaced. I’m willing to bet you can do the same in an afternoon or less. The benefits you get for your time outweigh the convenience of repeated upgrades in place by a longshot.



In the meantime, upgrades in place are useful and convenient, and they’re clearly the direction that Apple and Microsoft want us to go. Downloaded operating systems are easy to buy, easy to install, and easy to patch. However, before you decide to replace that laptop with Windows 10 on it that seems so much slower than it was when you bought it with Windows Vista installed, consider doing a clean install of Windows 10 first. You’ll be surprised how even that old hardware and a new OS can feel like new.