parallel vs serial
 

Would someone be able to tell me if Im going to have any problems with using a Y with 0.5 inch lines everywhere? Would the fact that the pump needs to feed to 0.5 inch lines through 1
half inch line stress the pump more than if it was one 0.5 inch line with everything in serial? Or would I be better off making the secondary line 3/8?

Im just thinking of relieving as much pressure as possible off the pump atm.

the pump won't feel too stressed about that. but if u don't have the flow to match, the airbubbles might feel all to happy taking care of some nice mood effects and dance in your tubes; instead of being blown into your airtrap or res. that is the only possible problem i know u could encounter (which you wo'nt encounter +/- if u go from 1 0.5" to 2 3/8"s in a Y). don't expect much good from mounting your rads in parallel though. if you're lucky, you will get about 1°C of difference.

This is for the NB and GPU block that Im considering adding in a second loop...

As for improving temps, ANY improvement would be good:( Im running at 47degrees at idle and around 51 load.

then i would suggest adding some more radiator power. i'm running at 35°C idle 42°C load with 2 heatercores + fans at 5V

You'll have to experiment! :D...

I'd try putting the NB & GPU parallel after the CPU, then join them again before the rad. use oversize Y's though, 1/2inch Y's have an inner diametre of 9.5mm!!, a 14mm~5/8" Y has 11.5mm inner.
............----GPU---
CPU---<..............>---RAD
............----NB-----

If it comes out right , like the above,**EDIT** ignore the(.......) dots, they're for spacing cause normal gaps don't work :shrug: ...