Do I want positive or negative pressure in my Mach II bottomcase?

[felinusz]

In my modified Mach II bottomcase, I have room for two 80mm fans, right above the condenser.

It would really be quite easy for me to install a couple of fans in there.

But, do I want the two 80mm's blowing intake for positive pressure (more air entering) inside of the Mach II bottomcase, or blowing exhaust for negative pressure (more air leaving) inside of the bottomcase? The only other fans in the bottomcase are the stock Panaflo M1A 120mm fans, one on the condenser and one blowing exhaust.

The 80mm fans would be positioned to be blowing directly over the top half of the compressor, mounted above the condenser in the front of the case.

Any thoughts?
Thanks in advance guys, I'll post pics when they're mounted :)!

[Thorry]

Fans can't actually create any pressure. The best flow IMHO is intake on the front and outtake on the back.

Pressure has got nothing to do with it, it's all about airflow (which is complex, ask F1 designers). The best airflow gets you the lowest temps at minimum noise levels.

[wdrzal]

air is much easier to pull than to push, both exhaust is best option.if set up allows.

[wdrzal]

oh fans do change pressure,it is the pressure differance that moves the air.

[felinusz]

So, with the fan setup shown in the below picture, is it better to have the 80mm fans blowing exhaust, or blowing intake?

Normally, intake would be the immediate and obvious choice for me given the fan positioning, but I've read that the air pressure (the amount of air entering versus the amount of air leaving) within the Mach I/II bottomcase needs to be balanced for the best results, due to the entire bottomcase acting as an almost completely sealed "wind tunnel".

Thanks guys :)

[wdrzal]

both exhausting would be best, but the warmer air should not be drawn over compressor

[Coyote]

axial fans pull better.
blowers push better.

[GuGaCoSa]

I think push/pull would be the best

[felinusz]

both exhausting would be best, but the warmer air should not be drawn over compressor

Intake it is then, which wil blow cool room temperature air over the compressor :)

[wdrzal]

you can draw air over compressor, best choice. draw air in front over compressor through condensor and out the back ,,

[felinusz]

The only problem is that the Condenser needs to be in the front of the case. Because of the Mach II control board with the 120VAC plug, mounted in the rear of the bottomcase, there is no room for fans at the back of the case :-/.

[skate2snow]

Actually, the results wont really change.... The only trick is to have no restrictions, so just put one blow and one pull... Blow on bottom, pull on top.... Put the best fan pulling...

[chilly1]

There is one issue that your fans can solve. If you are using this in a configuation where the case is on top and the fan in the front is intake across the coil you want the back fan to pull a little more air so that the warm air from the front fan and compressor wont enter the case.