hey thank you all for that answers!!
I have a Bequiet PSU at home. I bought it 02/2011. Do guys want to have the exact name?
No I won't re-use my case and DVD-R from my old PC. The DVD-R has an IDE port. The case is too unorganized and old
I get for the DVD-R the (LG Electronics GT60N Slim DVD+-R/RW)
and for the case (CoolerMaster 690 II Advanced).
No the calculation of 335W did not include the OC-ing, because I don't now the wattage of a 7850 or 2500k when it is overclocked.
I won't buy anything overclocked. But I plan to oc the 7850 and 2500K later on...
Thanks for all your support!