USB Voltage Output

[allosunshine]

Is there any way to find out what voltage my USB ports output??
The reason I ask is that when I connect up my Maxtor Mini HDD it doesn't work properly and when I try to charge my SATNAV it wont charge anymore. I tried both on our laptop and they both work fine on there.
Thanks.

 

[allosunshine]

The thing is they were working fine before. The only thing I can think of that might have caused this is that I connected another set of 4 USB ports to the motherboard for the back.
Could this have caused the problem??

 

[allosunshine]

cheers guys, i'll have a play with it tonight when i get home.