Make an OS X Boot Installer USB
Make an OS X Boot Installer USB installer
Prepare
1. Make sure you have internet connection.
2. A 8Gb USB driver (or bigger than 8gb). Whole process will format this drive, please make sure you don't have important data in this drive.
Insert Your Driver
Use Disk Utility Format Your Drive
Open: Applications-Utilities-Disk Utility
Format Steps
1. Choose your driver from left list.
2. Click "Erase" button.
3. Choose "Mac OS Extended(Journaled) in "Format" option.
4. Click Erase
1. Click "Partition" Button on the right side.
2. Click "Current" option.
3. Choose "Partition1".
4. Change the name into "Untitled", Choose "Mac OS Extended(Journaled) in "Format" option.
5. Click "Options" button down below, choose "GUID Partition Table".
6. Click Partition.
Download OS X YOSEMITE
1. This OS X is free, you can download from Appstore or other web sites.
2. If you download it from App store, system will auto-install it after download, please cancel it.
3. After download "Install OS X Yosemite.app", drag it into "Applications".
Make Your Driver Bootable
1. Open "Terminal", It is a App in "Utilities" folder.(Same place with "Disk Utility")
2. Copy and Paste this words in "Terminal"
sudo /Applications/Install\ OS\ X\ Yosemite.app/Contents/Resources/createinstallmedia --volume /Volumes/iPlaySoft --applicationpath /Applications/Install\ OS\ X\ Yosemite.app --nointeraction
3. Hit "Return"(enter) key.
4. Terminal will ask your code during this process, after enter your password, system will finish this.
Restart
1. don`t eject your driver
2. Restart computer and hold "alt" key. You will see the yellow icon after start.
3. Choose that icon, follow the steps, you can begin your clean installation now.