Dual Core, had the same problem.

I got 4x 1GB Transcend Axe RAM DDR1066+ after. However, it's damn hard to get DDR1180+. However, DDR1000 4-4-4 works flawless. DDR1200 is possible however it requires lots and lots of tweaking, which in the end just ruins it for me.

I love to mess around, but that much.

Im just thinking to get watercooling and get rid of the heatsink + RAM problem.

But there are enough nice kits which use normal sized heat spreaders, you just have to look around a bit