New
#11
have you tried cleaning and reseating your ram and cards yet?
if you're really worried about using an old toothbrush, use a new one. it's a useful tool to remove dust and crap from motherboard slots - a good size, a decent handle, and lots of control. or use canned air - but you're more likely to have a toothbrush around the place than a can of compressed air, or maybe not...
you can troubleshoot your ram by booting with only one stick at a time, or try something like memtest to give it a real workout.
troubleshooting your gfx card or mobo is more difficult.
i am a bit confused about the usb issue too...but you have to try one thing at a time to see if that works.