How do you know how much MA's your USB is capable of?

[jfall]

I have an A-Bit KT7 Raid board, I am wondering how much MA's the USB ports can handle? I currently have a Canoscan USB scanner taking up 500ma's and a Logitch Optical mouse taking up 100ma's. I know VIA has USB problems, my mouse turns off when I try to scan something, and I find my mouse stutters. I am thinking about getting a PCI USB card or a USB hub.. what do you think?

 

[xtreme2k]

I think it is 500mA per HUB? I am not 100% sure.

 

[lacunae]

i'd pick up a self-powered hub... they're cheap (4-port ~$20-40), give you extra ports, and take the load off of your computer's motherboard and power supply. also, if your case doesn't have front-mounted usb ports, an external hub is nice just for convenience for connecting/disconnecting devices.

as for the usb spec, i think 500mA sounds right, but i don't remember whether if that was per device or total. however, the amount of current that can be supplied by onboard (or pci card) usb ports can be limited by your power supply... if your p/s is smallish and just barely covering your basic system power requirements (mb/cpu/vid/hd/etc), then it might not be able to provide the full 500mA properly.

 

[jfall]

I guess I would be having some sort of problems trying to pull 600ma through it then.. I only have a 300w power supply but I have a cd-rom, cdrw, my hard drive, plus my geforce II gts etc. I might try a powered hub.

The only problem with the powered hub is that I am still not bypassing the VIA USB controller.. so I might still run into problems? My best bet might be to get a pci2usb card and then run a hub off that possibly?