CPU Fan direction Cooler Master K280, GA-990FXA-UD3, AMD FX-8320, Cooler Master T4 Heatsink

Question

I'm building my first computer, and this is what I have:

• Case: Cooler Master K280
• Motherboard: Gigabyte GA-990FXA-UD3 R5
• CPU: AMD FX-8320 8-core
• Heatsink: Cooler Master T4 Hyper
• Extra fan: second fan at the back of the case for exhaust

^{fan connectors are circled and identified  (Click image to enlarge)}

My problem is that the CPU fan has to face either up or down. It is not possible to place it in such a way that it pulls the air to the back, helping the two case fans.

My question is, in this case, what should I do? I see 4 options:

1. fan below the heatsink, pulling air away from the heatsink, downward

2. fan below the heatsink, pushing air into the heatsink, upward

3. fan above the heatsink, pushing air into the heatsink, downward

4. fan above the heatsink, pulling air away from the heatsink, upward

I must add the the distance between the heatsink and the top of the case is only 2 5/8 inches, and the fan is 1 inch thick, so if I was to place the fan above the heatsink it would be only 1 5/8 inch from the top of the case.

Any suggestions would be appreciated.

Answer 1

If you can change the orientation of the heatsink

Ideally, you'd have the heatsink rotated 90 degrees CCW from your photo, with the fan pushing through the heatsink, straight to the exhaust fan. However, I don't know if the mounts you've been provided would allow this, but this would be the perfect scenario from your image.

If you can't change the orientation of the heatsink

It's difficult to decide because none of the options are particularly optimal. Note that the fan should ideally be pushing air through the heatsink, rather than pulling.

Option 1 - Not the optimal configuration. Blows hot air straight onto the graphics card, and not too close to the exhaust fan.

Option 2 - Better, but now gathering heat from the graphics card.

Option 3 - Hard to say if this is a better idea, on first glance I'd say yes, but consider that hot air will be rising to the top of the case and there won't be much room for cool air to flow above it.

Option 4 - Likely the worst configuration. Hot air will be drawn towards the exhaust fan from every component, pulled through the heatsink and heat up the top of the case, as well as being a sub-optimal cooling solution with the air being drawn through the heatsink.

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I'd look carefully to make sure the heatsink definitely can't be mounted the other way around, as this would be ideal. If not, I'd opt for option 2 or 3, and closely monitor the temps under load for a short duration to be sure things aren't getting too hot.