This will be a category I visit every now and then. Think of it as a running list of things of such excruciating stupidity that the people who do them need to get their asses kicked. It won’t name specific names, unless I think that would be more funny than otherwise.
To start off…
People who put ATA/EIDE peripherals in a system and mix manual jumpering with Cable Select on the same bus.
Most PCs (practically all workstation-class) these days use EIDE/ATA drives. The IDE specification permits exactly two devices per IDE bus, a master and a slave. These designation helps the IDE controller and the devices figure out priority when both devices are trying to move data across the bus. In order to declare a hard drive, CD/DVD-ROM, or other ATA-compatible peripheral as either master or slave you have to move a small plastic jumper to bridge a set of pins. Which pair of pins you bridge tells the drive which position it is.
Some bright soul figured out that with a slight modification of the IDE cable, and with the appropriate smarts on the drives, you can use a method called Cable Select. Cable Select (a separate pin setting on compatible devices, which is pretty much anything IDE/ATA these days) tells the device that it is master if plugged into one position on the cable and slave if plugged into the other position. It’s fairly nice, since you set all your devices for CS and you never have to worry about conflicts.
You never want to mix the two methods. If you’re using CS, it needs to be used for both devices on the chain; otherwise, bad things happen. For example, two hard drives on the same chain, one as master and the other as CS, might cause severe speed slowdowns on the master drive and prevent the OS from ever seeing the CS-enabled drive.
If you are a person who has configured a computer like this, this is stupid. If you’ve done this to someone else’s system, then I will have to kick your ass, because it will one day be me (or someone like me) who has to fix it and explain to them just how stupid you were.
Don’t be that person.