To boot a Dell Dimension from a USB flash drive, for example a Clonezilla Live USB drive, connect the USB flash drive, power on the system, then hit F12 to get the boot menu when you see the Dell logo. From the boot device menu, select "USB Flash Device".
Boot Device Menu ================ 1. Normal 2. Hard-Disk Drive C: 3. IDE CD-ROM Device 4. Diskette Drive 5. USB Flash Device 6. System Setup 7. IDE Drive Diagnostics 8. Boot to Utility Partition Enter a choice: 1
You can configure the system to always attempt to boot from a USB device before the hard disk drive (HDD) by hitting F2 when you power on the system and the Dell logo appears to enter the BIOS setup. Under Hard-Disk Drive Sequence, you can put "USB Device" at the top of the list, if you wish by using the "+" or "-" keys to rearrange the order in which the BIOS will choose boot devices. You will need to put "USB Device" prior to "System BIOS boot devices" to have the system attempt to boot from a USB drive first. You can select "USB Device" and use the minus key to move it to be entry 1 in the list.
|1. USB Device|
|2. System BIOS boot devices|
|3. Hard disk drive (not installed)|