I understand how annoying it can be.
But a few further suggestions:
If OCUK have tested them and they seem to run fine, I would generally trust that but we weren't there and maybe sods law they worked flawlessly when they were tested.
My approach would be the following:
Get someone else nearby to try the cards in their PC (or in another PC of yours), if they still fail then it's going to very likely that they are actually faulty and somehow OCUK have missed something. (Maybe you tried this I tried to read all the posts). You can present this evidence to OCUK regarding RMA.
I would also try taking your entire setup out of your case and running the pc from a desktop / table, it is entirely possible that as it is so random that something is shorting somewhere with those particular cards due to their size, weight or the dreaded sod's law (even if there is no visible sagging). (again if you have tried this or it's just not possible then sorry)
If I was nearby I would volunteer to test the cards in my PC for you but alas I'm hundreds of miles away.
But a few further suggestions:
If OCUK have tested them and they seem to run fine, I would generally trust that but we weren't there and maybe sods law they worked flawlessly when they were tested.
My approach would be the following:
Get someone else nearby to try the cards in their PC (or in another PC of yours), if they still fail then it's going to very likely that they are actually faulty and somehow OCUK have missed something. (Maybe you tried this I tried to read all the posts). You can present this evidence to OCUK regarding RMA.
I would also try taking your entire setup out of your case and running the pc from a desktop / table, it is entirely possible that as it is so random that something is shorting somewhere with those particular cards due to their size, weight or the dreaded sod's law (even if there is no visible sagging). (again if you have tried this or it's just not possible then sorry)
If I was nearby I would volunteer to test the cards in my PC for you but alas I'm hundreds of miles away.