According to http://www.buildcomputers.net/power-...omponents.html , it is:

Solid State Drive SSD 0.6 to 2.8 W
2.5" Hard Disk Drive HDD 0.7 to 3 W
3.5" Hard Disk Drive HDD 6.5 to 9 W

According to http://www.tomshardware.com/reviews/...tb,3494-6.html
HDD power consumption can be roughly 3-8 W when idle