cpu: core 2 duo e6300 1,86ghz (with the e6600 stock cooler, if anyone wonders why, its bigger and i get it for free)
ram: ocz gold xtc pc2 6400 2048mb kit
mobo: msi p965 platinum
psu: hiper 580w
(the rest is not important in this matter)
what is a good clockspeed for the cpu and the ram?
The stock cooler on the E6600 is the exact same one you would get with an E6300. Theres no difference. I'd say with some luck you could get the 2.5ghz, maybe 2.7 without your temps getting to far out of hand. I would consider getting a different mobo though...