I have a laptop, to which i have a really generic notebook cooler connected to using the usb. can usb devices pull more electricity from the usb ports than they are designed to handle and thus *fry* the motherboard? if then i should quickly remove the cooler :$
In theory it can happen. But what usually happens is that the USB controller will either discontinue the power to the port to prevent damage, or the PSU will struggle and shutdown the computer altogether (not a Windows shutdown, more of a sudden blackout). Check the fan specs at the back. How much power does it draw? And are you using USB 1, USB 1.1 or USB 2?
USb 2 has more power available than earlier versions.
If you have a USB 2 device and plug it into a USB 2 port you should be ok.
I would not plug a usb2 device into a USB 1 port. (most manufacturers are cutting costs and redundency, margin of error, and protection are the first to go)