my wireless usb adapter is picking up the 20 mbps it's supposed to when it's the only device plugged into a usb port.. but as soon as i plug in my xbox controller or my external soundcard , the speeds drop to 15 mbps, and 10 mbps , and the device loses signal from 5 bars to 4
USB 2.0 has a maximum power output of .5 amps. If you connect multiple devices to the same USB hub they all will share that power. The easiest way to alleviate this would be to plug into a different usb port, or buy an externally powered usb hub.
Also if your wifi is only getting 20mbps it sounds like its being underpowered already as it should be getting at least 54mbps if it and your router are less than 5 years old.
sorry i must have phrased that wrong.. my cable internet speed is 20 mbps , 2 laptops in the house are getting the 20 mbps it should be getting , my desktop gets 20 mbps when the adapter is the only thing plugged in., but as soon as i connect other devices it drops to half. i have it plugged in directly into the usb ports on the back of the mobo , not the 2 front panel ones
On the back of your system board, you probably have 6 usb ports. 2 in line with the ethernet, and 4 in a row next to it. Additionally you have some in the front panel. The 2 by the ethernet are on their own hub. The 4 in a row are on their own hub, and the front ones are on their own hub. Just spread out your usb connected devices so they are on different usb hubs and the power problems will fix themselves without having to buy anything else. Each hub has a .5 amps of power to use.
If this doesn't fix your problem you may be running at usb 1.1 speeds. On some boards you can set the USB ports to 1.1 instead of 2.0 (although I don't know why anyone woudl want to.)
Normally it wouldn't but it does sound like your maxing out your usb's power. Try swapping the security fob with the wireless card. The soundcard is probably using up most of the .5 amps available, so with your wireless and soundcard on the same hub they would be fighting for juice. Keyboards, mice, usb memory sticks (the security key) use very little power, so this might alleviate some of your issues.