Butcher
Your Qtot are way overestimated, using Since87's pelt calculation excel sheet, i got a Qtot (using 100W from cpu) of 315W, instead of 401W. I also have the feeling that the estimated Q of the cpu is also overestimate, but I have no idea by how much.
Tho even with this lower Qtot, seeing temp around 0°C under load probably wont be possible unless you use chilled water. As far as I know, "ambient temperature" in the file is a reference to water temperature (or air in the case of air-cooled pelt). So the best you can do is play with the file and see how a pelt will work under different conditions. You will soon notice, that the better the wb, the higher the voltage can be put. On the other hand, you will get better results at low voltage in the case of high C/W wb, so a variable psu really can help you find the best voltage for your setup.
p.s. when I said Swifty I was refering to Swiftech
p.p.s. I dont know how accurate Since87's calculator results are, but since he probably based it on
this article I think we can trust it.