Oops, I clicked on Add before I was done.
If you have bad/incompatible memory, the problem could rear its ugly head in all sorts of ways. If I remember, I had some early Ballistix memory (which I purchased specifically for the Thermal-Sensor-On-DIMM feature) that I had problems with. I discovered that the memory required 1.65V and didn't work reliably at 1.5V. Once I configured for this, the problems resolved themselves. Note that this was with a DZ68ZV; I don't think I ever got it to work correctly in a DZ68BC (it wouldn't even work long enough for me to get into BIOS and make the configuration change)...
I assume you are talking about a tool to verify if a board has one of the bad chipsets. I had no idea such a tool existed. I just did a search for it, but I found nothing. You wouldn't happen to have a link? I found a Chipset Identification Utility, but it only works on 32-bit OS. And I found another utility, Board ID Tool for Desktop Boards, but that just gives the information I can find on the board sticker.
As for the memory, it's probably not incompatible, as it has been in the PC for five years or so. Bad is definitely possible, though. My theory, which changes by the hour, is that it was damaged slightly by my misadventure in OCing RAM which you helped me out of by pointing me to maintenance mode, though at the time you mentioned that it could also be the processor memory controller.
I neglected to mention before that the BIOS is 0160, the latest available.
It appears that my debugging was far too hasty. I stopped the W-7 installation at a certain point, but I later learned that the chkdsk could appear after either of the first two auto-reboots (or both). The memory actually made no difference.
So I tried installing on the Black HDD using the other SATA III port, which worked. Then I tried installing using a SATA II port (port 2), which worked. So it's port 0 which causes chkdsk, which makes sense. And I swapped cables to remove it from suspicion.
The only remaining question is, how closely related are the two SATA III ports, in other words, since one is unreliable, does it mean that the second one (port 1) may soon follow? I would imagine they are very related.