which prog? I dunno. I use speedfan v4.02 ?? and it agrees w/ my bios. If you are comparing before and after temps, stick w/ the same source. Be consistent.
Noise is why I switched also. Use 120mm panaflo L1A fans. Get a rheostat... a 5W, 100 ohm should work nicely, or a 7/off/12v switch. At lower voltages, those fans will be completely inaudible, even in the same room. My eheim pump is almost completely silent, and it sits next to me. Any sound you hear will be a vibration it causes. In a separate enclosure in a different room, you should be able to dampen it adequately.
I'm assuming that the Y in your hose happens once the hose reaches the case. For now, run the hose in series from the CPU, Geforce, Nbridge, HDs, Rad, Res, Pump. Then, you may want to simply get a bigger radiator. Use a fan shroud to distance the fan from the rad... at least one inch. This will improve performance and reduce noise. A cardboard box works nicely... use your imagination.
This doesn't have to be painful.
Well, it's almost midnight in SF, so that means it's almost 3AM here... goodnight... I'll check back tomorrow AM.
cheers