I have the MSI P7 Diamond 780i SLI Motherboard with 4x1GB OCZ1066mhz ram in dual channel. I can't clock past 3ghz and then it becomkes unstable. If I run 3DMark for example the system crashes. Anything over 3ghz then forget it, instant crash. I have heard of these processors reaching 3.2 to 3.4ghz easy. My cooling is ok as I am using an Arctic Freezer and the temps never go over 40deg even at 3ghz.
Any further questions please help as this is very frustrating
Try increasing the voltage of your ram "normally" 2.1 to 2.2 Volts is safe. I've done this on Crucial Ballistix DDR2-800 4-4-4-12 (2.2v) and Corsair Dominator 1066 5-5-5-15 (2.1v), but i'm not sure about OCZ never had the chance to work with them.
On some occasion (Intel chipset) you need to increase the MCH just a very few volts (0.04v for example) when you have 4 DIMMS to have a stable system it happened to me with a abit IP35-Pro. Don't know about nvidia chipset