I got an old Dell T3400 from an closing office a few days ago without a HDD. So I grabbed a 160GB hard disk from my old Laptop and installed Windows 10 on it. It works very well without any issues. But it only boots into Windows if I open and close the BIOS one time at boot. If I just power it on, nothing happens after POST message, so I have to power it off, turn it back on, press F2 to get into the BIOS, press Escape and Exit the BIOS to get into Windows.
I'm running BIOS version A14 (newest version, but it didn't work with the original A08 aswell). I already tried resetting the BIOS and re-inserting the CMOS battery.