help me to make fans work with modded GPU

[ioverclockers]

Ok this is my situation. I modded a Radeon VII with a morpheus II replacing stock 3x80mm fans with 3x120mm silentwings 3 ones (only two fans sit under the GPU, the third one is just on the chassis).

Now, I wanted the signaling being done by the GPU, not the motherboard, so to have the fans gear up only when the GPU needed them and not having them run at full speed all the time.

So this is my setup (see diagram) :

GPU -> Gelid CA-PWM-02 -> Gelid CA-PWM-03 -> PSU

I have a thermaltake commander for my case cooling, but I’m not using it for the GPU fans.

Basically this ought to work OOB !

The Gelid CA-PWM-02 is a PWM Fan Adaptor for VGA Cooler Fan.

On their site it states

Control the fan speed of 4pin PWM fan by the PWM signal of the display card. Features
The adaptor allows user to connect multiple PWM fans with PWM Y cable. It is suitable for AMD and Nvidia reference display card with 4 pin PWM fan header.

Now did I make a mistake with the (CA-PWM-03) PWM 1-to-4 Splitter ?

I connected the PWM connector to the CA-PWM-02 and one of the PWM Headers that has the fan speed signal to one of the 120mm fans, the other 2 PWM connectors (three pin) to the two other 120mm fans.

The molex connector to the appropriate socket in the PSU.

I wanted to have an independent power supply that wasn’t dependent on the GPU, in order to avoid any spikes or survoltage in case the Radeon VII wouldn’t be able to handle the voltage of the three 120mm silentwings 3.

Now, it simply doesn’t work. In the bios, the other fans appear without any problem, but I do get a CPU fan error and the GPU fans simply don’t show up. They never fire up neither (now this may be because I still haven’t installed any OS on this, just a hypervisor, so they might not get hot enough yet to have the GPU fire them up ?).

I tried to unplug one 120mm fan, but even with mere 2 fans, still no go…

Now, TBH, i followed commentaries on Amazon before buying this setup and it ought to work. On their site though, it’s stated that

This splitter enables the PWM signal input from the mainboard to control up to max. 4 GELID PWM fans.
Features
Connect 4 PWM fans to your mainboard’s CPU socket with direct power supply from PSU. Use multiple PWM splitter to connect 4 PWM fans and provide additional cooling as before.

Which kinda seems to say this shouldn’t necessary work with a GPU right ?

Now, what are my options ?

Any alternative to the Gelid CA-PWM-03 that would allow me to make my current setup work ?

Or, alternatively, to simply hook up a PWM Y-splitter (I have a few Noctua NA-SYC1 splitters lying around) to the Gelid CA-PWM-02 and directly to two of the 120mm silentwings 3 fans, hoping the Radeon VII will be able to handle the voltage ?

Thanks for any feedback on this !

https://postimg.cc/tnPnBK10

 

[Danny75]

Or, alternatively, to simply hook up a PWM Y-splitter (I have a few Noctua NA-SYC1 splitters lying around) to the Gelid CA-PWM-02 and directly to two of the 120mm silentwings 3 fans, hoping the Radeon VII will be able to handle the voltage ?

Should be no problem.

 

[ioverclockers]

well, how can i make sure the Radeon will be able to handle the voltage ? Any easy way to verify this ? Don't want to toast a radeon VII at its price !

 

[Danny75]

By asking AMD to confirm that the GPU fan header provides at least 1A like all/most other GPUs out there.

 

[ioverclockers]

basically did the other way around : fact checked Amp requirements for the silentwings on the site and they basically draw both under 1A, so we're good to go !

 

[Minstadave]

When I ran a 1080 with a Morpheus I just ran the two 120mm fans directly off the GPUs header. Found the mini fan header Y cable on the bay.

 

[ioverclockers]

oh great, that'd dispense with the gelid adapter i see. Anyway it works ok now !