j_cocker

That's what I have... As I mentioned earlier, the above also applies to old/faulty HDD. However it had no jumpers at all and worked as master (with a slave attached) for many years now without a problem. I tried the new HDD without jumper and with the jumper between pins 5 and 6 (10 pins) as suggested. Both failed to work... Don't think so. I partitioned the new drive to C (~50GB) and D (rest), and installed XinXP on C. They are. Only connected it to check that the slave and the cables are still working OK (which they are).

Yep, I tried both with the jumper out altogether (which seem to work with the original faulty HDD), and with the jumper in the Master w/ Slave position. Machine didn't boot in either casese despite new HDD having OS installed (and booting when the only HDD used).

I have an oldish Medion desktop that has a dodgy hard drive (bad sectors that cannot be repaired, and hence Windows sometimes fails to start). The machine has two hard drives. The one I am replacing is the one holding the OS (Win XP Home). The one I am replacing is one of these: WD2000JB (HDD1) The new one I bought is one of these: WD3200AAJB (HDD2) The secondary (slave) HDD is one of these: (HDD3) Barracuda 7200.7 | Seagate# In the original setup both HDD1 and HDD3 had no jumpers, which makes HDD3 the slave (see above link), and hdd1 the "Single or Master" as indicated in a diagram on the HDD itself. HDD1 is at the end of the IDE cable, HDD3 in connected to the "middle" connector. HDD2 has exactly the same pin/jumper diagram on it as HDD1, so I simply replace HDD1 with HDD2. I inserted a (legit) winXP Home cd into the drive and tried to install windows on the new HDD. However, the new (master) HDD it is not shown in the list of possible partitions, only the slave (HDD3). I looked at the BIOS, and the new HDD2 is there as master, with HDD3 as slave. I disconnected the slave HDD, and then managed to install winXP onto the new HDD without a problem. The machine boots into it without a problem. I then re-connected the slave HDD, and the machine will not boot, although the BIOS still reports the correct master and slave. I also tried without success: - Using a brand new cable. - both the new and the old HDDs (HDD1 and HDD2) have the same jumper diagram (see Image - TinyPic - Free Image Hosting, Photo Sharing & Video Hosting). However, despite what it says in the diagram everything worked just fine with HDD1 using no jumpers at all ("single or master" mode, rather the "master w/slave" mode). I tried the new HDD (#2) in both modes, and in both cases the machine refuses to even boot (although the BIOS thought that the master and slaves were set up correctly)... - To eliminate other possibilities I also re-connected the old HDD using my original setup and everything worked fine. Any idea what is going on?