I assume you mean Alpenfohn K2
There's nothing inherently wrong with the Shinobi. 2x front & 1x bottom intake is plenty of intake for most applications.. dependent on how much heat you GPU is dumping.
Suggestions for good quiet cooling:
*If you can, remove the cheese grate grills to reduce restriction and noise.
*Use fans with a decent static pressure rating. You hear all kinds of talk about cooler and radiators needing good static pressure fans but very little about cases needing them. The reality is most cases have needs very similar to coolers. Case intake fans start by having to pull air through a grill, than a filter, probably another grill. Than have to push the air through a HDD cage & HDDs, past wires, around GPU & whatever else is in case to get to the cooler. This all requires fans that can overcome pressure differential and keep moving air quietly.
*PWM fans controlled by CPU PWM speed control and possibly GPU PWM speed control. This is easily done with PWM splitters with molex power from PSU. Case airflow is dependent on CPU cooler and GPU cooler airflow demands. We need enough airflow to supply the cooler intakes with cool air and to remove the coolers' hot exhaust air out of case (so it doesn't mix with case air and heat it up). So if case fans speed up and slow down with cooler fans they supply more air when needed and are quiet when not.
*Often removing unused PCI slot covers will help GPU cooling.
*Raise case so there is 4-5cm clearance between case bottom and what case sets on. This is so the available intake area in square cm is similar to fan size area; 2x 120mm fans = 226sq cm. Circumference of 2x fans minus area between fans that no air can be pulled into either fan from = 56.6sq cm times 4cm = 226sq cm.
*3x good 120mm intake fans will usually keep everything nice and cool.. usually without needing any exhaust fans. If you have a window case with a side vent a side fan may help.. but not always. Should it be intake or exhaust? Try both and see which works.
If you are not using your optical bays adding an intake fan in them will improve cooling too.
Sorry for being so long winded.
