2: If any of the parts still work you could re-use them for a HTPC when you next upgrade.
3: No worries.
4: This strengthens the memory/memory slots as being the cause of the issue, as you know video cards use a lot more power than the Ram and so if the video cards had overheated or shorted the MB that area of the board would be damaged, unfortunately this does not stop the video card/s being damaged by other faulty hardware.
5: Some MBs will not boot if there is no Ram in Dimm slot 0/A, part of the reason why I asked how many sticks you have was so that I knew whether or not I needed to ask you to only use one stick at a time while testing and if slot 0/A had to have Ram in it at all times.
6: The generic PSU is fine for the most basic of testing.
No need for any apologies
We understand that computer problems can be stressful and I was merely offering a pointer for future reference
We know that the Ram is not right for the MB so let me know if you wish to continue with any testing please.
You are welcome