Your PC power supply has a 5V rail and you can access it through a sata drive power adapter.
| 1 | +3.3VDC | 3.3 V Power | orange |
|---|---|---|---|
| 2 | +3.3VDC | 3.3 V Power | orange |
| 3 | +3.3VDC | Enter/exit Power Disable (PWDIS) mode | orange |
| 4 | GND | Ground | black |
| 5 | GND | Ground | black |
| 6 | GND | Ground | black |
| 7 | +5VDC | 5 V Power, Pre-charge | red |
| 8 | +5VDC | 5 V Power | red |
| 9 | +5VDC | 5 V Power | red |
| 10 | GND | Ground | black |
| 11 | Optional | Staggered spinup/activity | black |
| 12 | GND | Ground | black |
| 13 | +12VDC | 12 V Power, Pre-charge | yellow |
| 14 | +12VDC | 12 V Power | yellow |
| 15 | +12VDC | 12 V Power | yellow |