Airflow for water WC build

[no_1_dave]

So, I've ordered some replacement tubing and water so I can flush the gunk out of my loop and have decided that I can revise the airflow at the same time. Below is a pic of my current airflow, as you can see I have 2 fans bringing air in (1 of which is through a small rad) and 3 fans pushing air out through a large rad at the top. The 2 fans bringing air in are running at 100% and the 3 top ones are running at only 30% each to keep noise down.

Please tell me what is wrong & how I should do it better.

Temps with this setup are fine, 65c - 70c on both 470s (overclocked) after hours of BC2 but I am getting fed up with dust buildup around PCI slots etc so I am considering positive pressure?

 

[no_1_dave]

Have you considered changing the back fan to an outflow instead of inflow? The way your current system is any airflow be it hot or cold is pushed through your rad on the top. Having the outflow on the back should lower the overall temp on the interior and thus push cooler air through the rad.

I have exactly the same case with a similar setup and I use the back as an outflow and the cooler air is sucked in through the top of the case into my rad.

Would that make it so I get a lot of dust buildup though?
Having a lot of air coming in and only 1 outflow?

Do you have a rad on the back also?
I would have thought if the top 3 suck air in than the back would need to be too otherwise it would only be very hot air pushed through the rear rad making it kind of pointless?