Completely different system and platform to you but I've got an i7 920 on an P6X58D-E with a Coolermaster 612S running 4x 4Gb Vengenace sticks. I didn't try the turn 90deg trick but did try just moving the fan on the push side up a little which worked fine but then meant my side panel on the case wouldn't fit back on securely. So I just removed the ridiculous heatsinks on the RAM on the two modules nearest the Coolersmaster which were causing the issue. You don't need them anyway unless you are planning on substantially overclocking the RAM. The heatsinks come off easily with a tiny amount of warming from a hairdryer, then unclip the little clips and gently prise off. My RAM is plain Vengeance, not PRo though but I imagine it will be similar in how the HS comes off.