Nicholas Bird

Advice with Cosmos II Asus X99-a U3.1 Fan Configuration

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Please could anyone advise on the appropriate way to configure/connect my Cosmos II Case FANs (supplied as standard) to my X99-a.


I would like the fans to vary speed depending on load (for a quiet system when not loaded)

I dont think i want to use the fan controller in Cosmos Case as i dont wish to manually select speed. The Asus board supports a fan profile, so i think i want to attach case fans to the board.


The board supports

1 x CPU Fan connector(s) (1 x 4 -pin)

1 x CPU OPT Fan connector(s) (1 x 4 -pin)
4 x Chassis Fan connector(s) (4 x 4 -pin)
These i will use for the Noctua Nh-d15 pwm fans.

1 x CPU Fan connector(s) (1 x 4 -pin)

1 x CPU OPT Fan connector(s) (1 x 4 -pin)



4 x Chassis Fan connector(s) (4 x 4 -pin) on the motherboard.



Can i attach 3 pin Cosmos Case Fans to 4 pin Motherboard headers?

Will it be possible to specify a fan profile to alter the speed of the Cosmos fans based on load using the asus config?

Is there a better way to achieve an automated cooling/noise result.



The case will have all drive bays populated with 5400 rpm drives.

The gpu will be non blower 7970 initially, always non blower if upgraded, always single gpu.

The cpu will be 5820 oced to 4-4.5Ghz

There will be a samsung sm951 in the m.2 slot

There will be 1 add on raid card for external chasis.

If i can decrease noise significantly through adding more lower rpm larger fans, then thats an option.



just found two noctua 120mm fans so will probably add those to side as Intake.

The hdd fans down bottom do not have long enoough leads to get to motherboard.

Consequently ill probably put the hdd and perhaps the side fans on minimum on the cosmos fan controller.



thank you for any advice.

Build starting tomorrow...

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So attaching the 3pin case fans which reached to the motherboard was no problem. Had to buy a fan extension cable for the front fan. Bit of an oversight for such an expensive case, given the fan profile of a motherboard is probably preferred to the low medium high of the cases controller.


in the end i ignored everyones advice above :-), i put all the fans on the motherboard except the side and hdd fans, which i put on the controller on low.

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