I have been searching the forums and can not find a thread for this so I apologise in advance for any duplication. Because I help with PCs in schools as a hobby, I ended up with 3 IT rooms of scrapped …2Bs and a whole lot of systems they wanted me to refurbish to “homework PC” standard (at least 2GHz processor, 2GB ram, 40GB hard drive, TFT Monitor, keyboard, mouse) for the school to sell at £50 for funds. The parents in the know requested a magic drive. I had tested all the available ones and rejected any that did not read non-standard disks reliably and did not pass the laser alignment test or showed any other symptoms of later problems. Putting the systems together, I found some worked and some did not. Being recycled ram, my first thought was a subtle pattern sensitivity, but swapping the ram between working and non-working base units made no difference. The next thing I noticed was that all the non-working had 40 wire IDE cables so I found 80 wire for all of them. This only brought some of them to life. The next pattern was that the remaining failures originally had CD drives fitted. Their bios was from before DVDs became common so I flashed with the latest and they worked. On the next batch I tried to predict. Most 40 wire, original bios combinations failed. Tried bios first and cable first but neither, on their own, helped. So far (17 systems) I have needed to do both. Hope this helps.