Well I'm on my 15th custom built (by myself) PC (including case modding - cooling + air flow). The worst hardware I ever had was a Promise Technologies Caching IDE hard drive controller. Basically a 286 + 16MB or RAM between my system and its hard drives.
Total piece of **** that cause disk errors, bad ones, every few weeks. An this was the good old days of Window 3.0, Win 95 and Win NT 3.5 argh. Forget plug and play and re-mappable I/O address and IRQ assignments. You had to guess to avoid conflicts and if your guess was wrong your system halted and it required a total operating system re-instal. It took about 300 hours to get it operational!