Powered USB hubs over non powered usb hubs?

Can anyone tell me why an AC powered hub is better than a USB powered hub and what the advantages are?
 
I'm looking at two on ebay and am slightly confused as they seem to be identical apart from one doesn't come with an AC power supply although one can surely be used if they are the same yes there is an £8 price difference so I was thinking it would be cheaper to buy the one without the power supply and then et the power supply separately.
 
These are the two I'm looking at
 
USB powered hub
 
AC Powered hub
 
Of the devices that will be running through it only one is actually USB3 but I figured if I'm going to buy a new hub it would be better to have a USB3 one for future hardware.
 
 
Any thoughts?
 
 
Cheers
 
Steve

fireberd
The USB port(s) in a PC can only supply a limited amount of power.  Depending on the USB devices connected to a hub,  they can exceed the available power and the devices will not work or work properly.   Best to always use a "powered" USB hub to avoid any potential problems.

+1

Cactus Music
USB 3 was introduced not only for faster trasnsfers but it supplies a lot more juice, look it up. 

 
That's kind of why I was asking as I'd heard that too but does it supply enough extra juice?
This is a 7 port hub and although it might now always be running 7 devices I was kind of hoping
it might carry enough power not to need a separate power supply.
 
Still the hub I have listed can have a power supply if required.
 
Steve
 

Thanks RT
 
I'm not sure if a new hub is the answer to my problem.
 
The problem I keep having is with my wireless mouse, the hub is sat about 40cm from the mouse and yet
quite often the mouse movement is very poor and unresponsive and at other times it just doesn't work at all.
I've been using this powered 7 port usb 2 hub for about 5 years now and was thinking maybe it was at fault so decided replacing it might (hopefully) be the solution.
 
Also my ps2 keyboard died recently so I'm borrowing a cheap generic usb one and that was working via the hub for a while but right now it isn't so I just don't know what the best thing to do is but I think I'll be getting a ps2 keyboard again as I don't mind having a corded keyboard but I hate corded mice so that has to be wireless.
 
It's been driving me crazy for far too long though
 
Steve

My USB 2 quad capture and APRO keyboard both use 500 ma each. That's the max current for USB 2 so they can't share and require their own ports. I use my powered hub for outboard stuff like mice and receivers for wireless keyboards. USB is weird. I have had to try different configurations to get everything working well. Some devices just don't like certain ports. No idea why, but when something acts up I check the batteries (if req) and try another USB port.