USB device won't let computer boot

[Funkyd04]

I made this thread about the computer not booting

http://www.tomshardware.com/answers/id-3121541/black-screen-bios.html

upon messing around with the computer, i noticed it would boot when nothing was connected, but not when i plugged everything back in. Trial and error showed that the PC would not boot if my USB camera was plugged in, no matter what usb port i used. The computer was showing a black screen and not even entering bios, with the VGA led light lit up on the motherboard DEBUG lights. I've since plugged everything back in including my 390x and everything is working great. SO what's the deal? How could a USB camera not allow the computer to boot?

FWIW, i have a usb mouse, keyboard, steering wheel, and racing pedals ( i'm an avid sim racer ) and those don't seem to cause problems.

 

[BadActor]

My guess is there is a short in the male end of the USB plug and it triggers some sort of protection on the motherboard.

 

[bethel95]

It's a long shot (and more than a bit strange), but maybe the problem is in the camera itself. Is it new to your setup? Did the boot problem start after you first plugged it in, or perhaps after it got a firmware update?

Here's what I'm thinking: USB devices report to PCs what their function is (or are, as they can identify themselves as more than one kind of device)--this can be set in their firmware to any kind of USB device, really. I'm wondering if your camera is reporting to your PC that it is a data storage device (in addition to being a camera). This would be weird, but then manufacturers do really weird things, at times. If so...

The next part depends on how your PC's BIOS/UEFI is set up. If you've got the boot configuration set to check for a bootable USB device before booting from the HDD/SSD (not at all an unreasonable thing to do), then if the camera is reporting itself as a data storage device (i.e., the PC thinks it's a USB flash drive), then the PC will try to boot from it (and fail, of course).

You could test this by plugging in a bootable USB flash drive (one that's previously worked as a boot device) instead of the camera, and restarting your PC. If it boots to whatever is on the flash drive, then there's a good chance we've identified the problem. (Or you could plug your camera into another PC that's set to boot first from a removable device--if it fails to boot up, that would also confirm the camera as the culprit.)

If you don't have a bootable USB flash drive, you can create one using the Rufus utility (just be sure to use Rufus to both make the flash drive bootable and to install a copy of FreeDOS on it, so there's something to boot into). One caveat on this: It's best if you use a flash drive that's at least 5 years old, as many (most?) of the USB flash drive manufacturers started making their drives self-report as hard drives, not removable drives, several years ago. A newer flash drive might not boot your PC, even after being properly configured and even if the PC is set to give a bootable, removable storage device the first boot priority (because the PC doesn't see it as a removable device). Unfortunately, there's no way that I know of to know whether a newer USB flash drive will exhibit this behavior before you buy it (I've seen in in newer SanDisk, Lexar, and Verbatim flash drives, though).