The problem is that the 45 nm CPU's have a pretty small cooler. It has very little reserve capacity. And the 3.5 - 3.6 GHz you "heard" of, what were the CPU load or idle conditions? I would be very surprised if you can get much past 3.0 GHz with the stock HSF under fully loaded conditions.
You should be able to reach at least 3.6 GHz and possibly 3.8 - 4.0 GHz - with a better cooler.
This should be your first stop.
Core2 Overclocking Guidehttp://www.tomshardware.co.uk/forum/259899-11-core-overclocking-guide
Next stop should be a guide for your particular motherboard. Google is your friend.
Go through the guides. Then take your core voltage off Auto and set your memory voltage to factory recommended values. Change the System Memory Multiplier (or whatever your BIOS calls it) from AUTO to 2.00, 2.00B, or 2.00D - whichever you need to set the Memory Frequency to twice the FSB. Then when you increase the FSB, the memory clock will rise in in proportion with it. At an FSB of 200 MHz, your memory clock should be at 400 MHz.
Download CPU-Z to check your FSB:RAM ratio. It should be a 1:1 ratio.
Don't exceed 1.45 volts on the CPU core and don't exceed load temps of 70 C.
And remember, YMMV.