I have an LED strip being controlled by an Arduino and powered by a molex connector within my PC. I'd like to have my Arduino connected to my computer via USB 24/7, however when I do this, the molex grounds itself through the USB connection when I toggle the switch to the off position, so the LED strip does not turn off when I want it to. Also, I don't feel comfortable grounding molex through USB. Is there any way around this? I have a reasonable background with electronics, but I'm just not sure what to do in this case, and I couldn't find anything on the internet. Thanks.