ok I have a 6750 and love it, but in my experience mine is not really stable at 3.6 for too long I leave it at 3.4 for sometimes days in a row and it never has problems. First up what mobo do you have? i have a p35 and it works well. max ive got mine at is 3.72
My first Core2 system was an E6600 in an eVGA 680i motherboard running at 3.6 GHz at 1.45 volts, P95 stable for 24 hour test run. Unless you have a higher than average VID, you both should be stable at 3.6 GHz.
I had my E6750 rock solid at 3.7GHz with 1.4275Vcore and 3.6GHz with 1.3875Vcore. I went with 3.7GHz even though it was less efficient. There are some stickies in the overclocking section here that have many useful tips on how to overclock. Reading can't hurt...or can it?
I have Q9550 and Q6600's running at 3.6 GHz and an E5200 running at 3.78 GHz.. I do not exceed Intel's recommended max voltage and temps. Well, except for the E5200. I pushed vcore to 1.50 volts. No joy. I am brickwalled at 3.78 GHz.
---------- Overclocking since 1978 - Z80 (TRS-80) from 1.77 MHz to 2.01 MHz
It takes a lot of guess work now days even more than in the golden age to get them just right when overclocking. I had to really tweak my ram timings to triple 4 by 12 with 15 bank cycle timing just to get the rig to run sli with out the crappy lag.