Fractal Design Core 500 fan setup?

[gsilver]

So, I have a Fractal Design Core 500 that I'm going to be using as my new desktop case (downsizing from mATX, and it lets me keep my PSU and cooler. The case has the motherboard run flat, and has a top bracket for two fans or a 240mm water cooler, and a fan in back

I'm using a Heligon HE-02 cooler, which is an absolute monster of a cooler. It barely fits in the case, but it does indeed work. Now, it blocks the use of full-sized fans both above and behind it, but slim 140mm fans should work. While I'm deciding what to get, I'm trying to figure out the optimal fan configuration.

Right now, I have the following setup:

Back fan: 140 mm fan (bolted to the outside; too wide to fit inside)
Top-back: empty
Top-front: 120mm radiator for an Arctic Accelero III Hybrid, set to exhaust
There is also a small fan on the VRAM of the graphics card, set to intake.

Temperatures are pretty good with that setup, but obviously, I need to swap the external 140 mm fan with one that fits inside of the case.

Now, I've heard that negative pressure is a bad thing for cases, so I'm not sure how I should orient the fans.

Should it be:

(Positive pressure, but side-by-side fans running in opposite directions)
Back fan: Slim 140mm intake
Top-back: Slim 140mm intake
Top-front: 120mm Radiator exhaust

Or: (negative pressure)
Back fan: Slim 140mm intake
Top-back: Slim 140mm exhaust
Top-front: 120mm Radiator exhaust

Or: (positive pressure)
Back fan: Slim 140mm exhaust
Top-back: Slim 140mm intake
Top-front: 120mm Radiator intake

Or: (slightly negative pressure?)
Back fan: Slim 140mm intake
Top-back: Empty
Top-front: 120mm Radiator exhaust

I read someone who had something similar to #3, but their temperatures were way higher than mine, so I think that it's a very bad idea.

Thoughts?

 

[gsilver]

Ok, so I worked with the fans a bit.
Running a Be Quiet SilentWIngs 3 over the Arctic Accelero III's radiator as exhaust, and two Prolimatech 140mm slim case fans (top exhaust, rear intake), I'm seeing my GPU stabilize at about 70c running Doom (which has 100% GPU utilization) when I set up a fan curve to run it at 27% at that temp. I left the CPU fan curve at bios default, and it maxed out at 62c. Finally, I removed the top fan cover from the case, as the fans are exhaust, anyway. It could probably stand a filter in back, but I'll track one down later.

That doesn't sound too high, and it's pretty quiet in this configuration.