Thanks, I sure will! Have been sending a couple of emails back and forth with my webshop yesterday. Haven't come to a final agreement yet on the RMA. But they already offered to take in the motherboard and ram. So we're on the right way. Just want to make some clear agreements in advance.
I would like to add some more info to this thread. Though not to find out whether RMA should still be done, that is obviously a YES.
Yesterday evening I decided to run some more memtest at 1066Mhz 7-7-7-20 1.64v on the ram and all other timings on auto (tRFC is 60 this way with 1T command rate, qpi/vtt voltage on auto also). This was recommended by my webshop so I tried it (whether this OCZ kit likes tRFC of 60 is debatable, but it is at 1066Mhz though). Also, I've put the CPU vCore back to auto as well, to exclude that from causing any problems. Now, memtest would freeze in a seriously messed up way:
http://img8.imageshack.us/img8/2663/20101124190714.jpg (non-coldboot)
Also, I had two freezes yesterday during gaming. One freeze ended in a BSOD with driver irql not less or equal. The same type of freeze I've been having since this new kit (though the first crash with a BSOD). I've seen various people on the net getting this (the type of bsod) also with ram issues. So I'm also leaning towards that still, as my drivers appear to be sorted.
This morning I did another memtest coldboot on the same settings as mentioned above. And guess what, errors at 1080.0MB range again (which also happened at rated specs), this time test #4. Again faulty ram seems plausible as the errors have been reproduced in the same range and solely this range, so far. Unfortunately I will be away for a few days so I won't be able to test these modules individually. But one would expect to see just module 3 from slot 5 (tested in any slot of course) to throw errors when tested alone and the other two to be clean. Here's the screenshot of this morning, after which memtest also froze. I guess if I would let it run for a longer period of time, it might end up as in the screenshot above.
http://img26.imageshack.us/img26/8550/20101125075801.jpg (coldboot)