Loop design
 

I've been thinking about loop design for my next computer (still at least six months away) and came up with one particular concept that feels wrong, but I don't know why.

Flow cycle is Pump -> Rad -> 2 outlet CPU block -> Split flow section -> Pump
One half of the split flow section is just the GPU block, while the other half is the NB -> HDDs (2 in RAID1) -> Res.
The rationale for this is that the GPU will need more cooling than the NB/HDDs and that I would like to use an Aquatube as the res - which will unfortunately put a big flow restriction in the system if all the water goes through it as it only has 1/4" internal diameter barbs. Also fitting the plumbing required if all the water goes through it would be quite bulky. Having the res at the top of the case should also help prevent the pump from cavitating.

The main questions I have with this are if the CPU block will be badly disturbed by significantly different flow rates out the two exits, and if there will be any problems associated with only having an air trap on one half of the loop. This whole system looks too neat a theoretical package, so there must be something wrong with it!

The basic aim of the system is to cool what will probably be a fairly fast (probably not overclocked) PC as quietly as possible.