Originally posted by: Aztech
So are there any that don't need a power adapter? Ones that get their power from the USB port?
Yes, but they are only reliable for notebook/laptop hard drives, and only sometimes at that. Because the USB port provides I think .5A of 5v power. This isn't enough for most hard drives, especially if it has to convert the 5v to 12v.
So if you want to go that route, get the USB cases that are small, that are the 2.5" laptop hdd size. But also make sure to get ones that CAN be powered by other sources as well if need be. Like some have 2 USB plugs so they can take power from 2 usb ports. Some have keyboard plugs because usually the keyboard port on a laptop is not used, and if it is the keyboard doesnt take all the power from it so it can be a passthrough for a keyboard.
Or some just have a plug that you can plug a little ac adapter into if nessasary.
For instance here's a 40 gig HDD for $72:
http://www.newegg.com/app/View...=22-149-014&depa=1
Notice that it is 2.5" laptop hdd and has only 4,200 RPM instead of 5400 or 7200 RPM. Usually the 4200 RPM drives take much less power.
http://www.newegg.com/app/View...=22-149-016&depa=1
Here's an 80 gig for $132 that is similar.
Yes laptop hard drives are much more expensive because they are small.
Many of the 2.5" USB cases even state this on newegg
"Application: Any 2.5" Parallel ATA Hard Drive with 4200RPM (Notebook size HDD up to 9.5mm)"
Here's one that takes power from an extra USB port:
http://www.newegg.com/app/View...=17-145-368&depa=1
And here's one that takes power from USB but has a plug on the back where you can plug in 5v adapter if you want to:
http://www.newegg.com/app/View...=17-145-329&depa=1
And here's one that has power from a PS2 port but has optional plug for external power
http://www.newegg.com/app/View...=17-146-304&depa=1
Some of these things come with little cases and other accessories and thats nice to have if you want to carry around extra storage for your laptop in your laptop case without adding a ton of weight and stuff.
Now am I right to be so concerned about power? Well let me put it this way, I have one with a 4200 RPM drive and it works most of the time. Sometimes some computers wont pick it up as USB 2.0, other times it wont be picked up if its in the USB port while the computer is booting, other times that is the ONLY way it can be picked up by the computer, if you put it in when it boots and not when XP is already running. It depends greatly on the computer and its kinda a hit and miss. The laptop I used it on had no problems, oddly enough it was the desktops that sometimes had these funky things. And that was one that had 2 USB plugs so it could take extra power.
So, there's a little rundown for you on some options without external power.