Ok mate, again thanks for the patience and trying to help, can't believe this has happened. Thought it was a 5 minute job
It should have been - i'm probably almost as gutted - I feel really bad for you.
If you do a search on installing new memory problems - you'll see that quite a few end up with a dead PC. But this
isn't the norm! People only post when they have a problem.
For every 2000 upgrades in 'old' systems i suspect only 1 snuffs it (complete guess - but you probably get my point) - and that may be because of a MB, HDD, PSU etc...
This really should have been a straight forward upgrade - worse case scenario, should have been, the memory was incompatible and you would have stuck the old set back in - and then back up and running.
I know you did the ACHI change but even if that had corrupted the BIOS the recovery system should have worked - same goes for the memory.
If i had to guess it may have been a combination of the two - but who knows - it could yet prove to be a shorting issue due to pressure on the MB of inserting new memory and your description of the risers.
But, unfortunately, there is the very real possibility that something has died - and the main component under suspicion is looking like the MB.