Question Two Systems in One Case (Lian Li DK07) - Sharing Fans

[Small_Town_Gamer]

I'm planning a two-system build in a Lian Li DK07 desk case, with an AMD system on the left and an Intel system on the right.

My airflow will be from front-to-back and left-to-right. For this to work, I need all case fans on at all times, regardless of which system I am running. I may even want to leave the fans on for a bit when both systems are off. I need to be able to turn case fans on and off (and ideally, to adjust their speed) from outside the case.

How can I do this?

 

[Lutfij]

How can I do this?
Have the fans hooked up to a molex/SATA power input only and no motherboard input. You could also have 3pin fans hooked to a PWM harness, the lack of the PWM signal will cause all 3pin fans on said harness to run at full blast.

 

[Small_Town_Gamer]

 

[Small_Town_Gamer]

How can I do this?
Have the fans hooked up to a molex/SATA power input only and no motherboard input. You could also have 3pin fans hooked to a PWM harness, the lack of the PWM signal will cause all 3pin fans on said harness to run at full blast.

But then I have no way turn off the fans (other than turning off power to the PSU), correct?

 

[williamjeremiah]

I would simply use the fan headers on either or both motherboards and control the intake / exhaust with either the board's UEFI or utility fan control.
One could, for example, dedicate one PC for the Intake and the other PC for the exhaust.

 

[dwd999]

You could consider a few of Noctua's NA-FC1 3-fan controllers:

https://noctua.at/en/na-fc1

 

[USAFRet]

For this to work, I need all case fans on at all times, regardless of which system I am running.

Somehow, the fans need to be on their own power supply.

OR...

Some sort of switchbox, to choose which PC will run them.

 

[punkncat]

You could run a separate 12V power supply for the case fans and use a fan controller to ramp up or down the speeds. IMO something like Altronix already set up for things like camera or door controller power would be great but significant level of overkill. You could technically use something like a plug in (box) transformer if you calculate the required amperage.

 

[Jackconnor]

Thank For Sharing this

 

[Paperdoc]

The "fly in the ointment" here is that there is NOT just ONE PSU. That desk / case system holds TWO completely separate systems, each with its own PSU, and hence each with its own power switch. If OP wants ALL case fans to operate at all times (with or without speed control), then he / she needs a separate power supply (and speed control?) independent of either mobo. For that one needs a 12 VDC power supply able to supply a max current more than the expected total max current of all case fans used. IF speed control is required, too, then that output of that power supply module should be capable of changing the output VOLTAGE based (probably) on a MANUAL control knob. Then the FANS can be simpler 3-pin (older style) Voltage Control fans since they will NOT ever receive a PWM control signal. Some custom wiring may be needed to connect the output of this power supply to standard computer 3-pin fans. Such a system will NOT be able to display the actual speed of any of the fans. But if it has (or OP can connect) a Voltage meter, that info can be used as a guide to manual settings. NOTE that such fans normally can STALL if supplied with a Voltage less than 5 VDC, so some way to limit the minimum power supply module output might be needed.

This has NOTHING to do with cooling systems on each mobo for the repective CPU's. Those each SHOULD be connected to the mobo CPU_FAN header since they are used solely for cooling one mobo's CPU and SHOULD be controlled only by the tempertature sensor inside each CPU.

 

[williamjeremiah]

In my opinion, this is being over thought on.
From my perspective, as long as there is constant airflow and positive pressure to facilitate the intended direction of dust filtration. --Of which could be controlled by either system's fan headers, using a flat curve for a static speed or run them off of SATA power and add resistors accordingly. It doesn't matter which system is assigned the case fan duty. If the case was split into two separate chambers, it wouldn't be any different than having two PC's.
Then each system's CPU fan/s can have their own separate fan curves, as usual.

 

[kanewolf]

I'm planning a two-system build in a Lian Li DK07 desk case, with an AMD system on the left and an Intel system on the right.

My airflow will be from front-to-back and left-to-right. For this to work, I need all case fans on at all times, regardless of which system I am running. I may even want to leave the fans on for a bit when both systems are off. I need to be able to turn case fans on and off (and ideally, to adjust their speed) from outside the case.

How can I do this?

Maybe a relay. If power supply 1 is active the relay is energized and the output of the relay is switched to power supply 1. If power supply 1 is not active, then the output of the relay is power supply 2. If it is active, then the fan controller connected to the relay is fed from power supply 2.
A single pole double throw relay.

 

[dwd999]

Perhaps a 3rd power supply; it doesn't have to be very powerful or expensive, just something low power that could be left on all the time to provide sata power output for some Noctua NA-FC1 3-fan controllers.

 

[thestryker]

I think the intent of the design is for each system to be setup mirrored so you don't actually have to run all fans at all times. From looking through the manual it's clear the sides are intended to be intake with exhaust at the back. I can't imagine the front being used for anything other than intake.

I'm not sure what the goal of the left to right air flow strategy would be since the sides are very far apart and the fan RPM required to push that far would be extremely high not to mention all the turbulence being caused.

As far as controlling all fans from each system I can't think of a simple way to do this without some sort of independent power supply and fan controller.