first time water cooling setup with routing question

This is the first water cooled system I have built and I’m not quite sure how to route the tubing. I’m installing a Koolance Exos 2 and the CPU block has 10mm fittings while the GPU block has 6mm fittings. I’m probably going to put the CPU first in the loop and the GPU second (it’s a bit easier to route that way). The first option is to split the 10mm hose leaving the CPU into two 6mm hoses and route one of them through the GPU block with nothing on the second loop and recombine them before they go back to the reservoir.


<--------10mm-------><---X2 6mm---><--------10mm-------------->
Res.--------CPU---splitter----GPU----splitter----10mm----back to Res.

The second option is to use an adaptor to convert the 10mm hose leaving the CPU to 6mm then convert back after the GPU block.

<---------10mm-------><----------6mm--------><--------10mm-------->
Res.--------CPU------adaptor------GPU-------adaptor---------back to Res.

(I hope the pictuers help) Basically I don’t want to overstress the system by constricting the hose to much at one place but If I split the hose into two I think I will probably lose a lot of performance because of reduced flow to the GPU. Any tips as to which would make the better loop would be appreciated. Thanks in advance.