and do you think fx 4600 quadro can handle latest CAD applications like: Autocad plant 3d 2013, Autodesk revit mep 2013, Autocad 2013, Autocad Revit structure 2013, and Autodesk navisworks manage 2013??
Two HD 7850's in crossfire and even overclocked will only consume a little more than 400 watts.
By 400 watts i mean not just the graphic cards but the whole system power consumption provided the CPU is not overclocked.
The Cooler Master M2 series are pretty damn stable and at 75% to 80% load they can even achieve 90+
efficiency. Don't worry it will easily handle two HD 7850's
The CM 600w that you mentioned can handle your fx4600 but lets not forget that this cheap PSU with cheap components and very bad voltage stability under load. So it might cause you problems every now and then especially during electrical fluctuations or power outages.
I recommended you getting a cheap and good quality PSU like the Corsair CX430 V2 for this system.