Connecting a hard disk causes computer to not even POST

Question

As a power user and a long time computer enthusiast, I'm flabbergasted by this problem. I've seen many things in my lifetime, but this one is new to me.

This is a long post, but an interesting problem.

A friend of mine asked me to fix his computer which, all of a sudden stopped booting into Windows 10.

Just a quick overview of the PC specs:

• ASUS P8H61-MX motherboard
• Intel i3-2200 CPU
• A low-end Asus GPU
• 8GB ram (2x4GB)
• Kingston 120GB SSD
• Toshiba 1TB HDD

The problem was Windows started to boot, but right away gave an error "A required device isn't connected or cannot be accessed". Pressing F8 or ENTER just reloaded the screen.

Both, the SSD and the HDD were detected in BIOS.

At this point, I decided to try and fix the Windows installation. I booted a Windows 10 USB key and selected "Startup repair", which had no effect.

I tried manual steps (bootrec /fixmbr, bootrec /fixboot, bootrec /rebuildbcd).
The rebuildbcd command found my Windows installation (on the SSD) and offered to add it to the boot catalog, which also failed with the error message The requested system device cannot be found.

After a couple of more tries (booting just with the SSD attached), I gave up and decided to reinstall Windows 10 to the SSD.

Before I did that, I wanted to copy all the files from the SSD to the HDD.

Easy-peasy, I re-attach the HDD, boot a live Ubuntu installation, mount all the partitions of the SSD and the main partition of the HDD and rsync the files from the SSD partitions to the HDD.
For good measure, I also do a dd image of the whole SSD to an image file to the HDD.
Both, the rsync and the dd command completed without issues.

I unmount everything and shut the computer down. I had some other stuff to do, so I leave the computer off, waiting for me.

Couple of hours later, I get around to it, turn on the PC and am met with a quick flash of the "American Megatrends" logo and then a black screen. Nothing.

After some head scratching and trying different combinations, I come to the conclusion that I get in this situation if the HDD is plugged into the motherboard. Disconneting just the data SATA cable make the POST OK. This is where I'm now stuck. I've tried the following:

• ran Memtest86, RAM is fine
• upgraded the BIOS to the latest version, loaded optimised defaults
• an SSD connected with the same SATA power and data cable to the same SATA port works
• a different HDD, connected to this PC, works
• this HDD, connected to a different PC, works
• switched the SATA cables and ports, still nothing
• after clearing CMOS, the mobo got set to the default of "Show full screen logo". In this mode, I don't get a quick flash, but get stuck at the logo, when the HDD is connected.
• hot plugging the HDD while booted into Ubuntu live, the HDD works
• I removed the GPU and used the integrated one to no avail
• I switched the PSU, same problem

Any ideas?

Answer 1

I decided to not waste too much time on this any more.

I connected the HDD to another computer and backed up the data to a NAS, then did a quick sgdisk -Z /dev/sdX, which did the trick (zaps the MBR and GPT structures).

Fun fact, merely converting the disk to GPT and zapping just the MBR made the disk to be detected in BIOS and the computer to boot. But then, if I rewrote the MBR with sgdisk, the problem was back.

Now, after zapping all the structures and initialising the HDD in windows, creating a single NTFS partition, the HDD gets detected and the computer boots normally.

But one major problem remains ...
the geek in me will never be happy, not knowing what was wrong :)

I do have a dump of the "corrupt" MBR, but I lack the time, knowledge and willpower to analyse it.