Correct approach to plug a 240mm aio in with NZXT G12

[Guptilious]

Hi,

PC Specs
OS - Dual boot of Ubuntu 20.04 and Windows 10
Case - Cougar QBX
CPU - AMD Ryzen 9 3900x
CPU Cooler - H100i XT ( sits on top of the case
Motherboard - Asus Strix B550-I ITX
GPU - 1080ti
PSU - Corsair SFX 600W

I recently won on ebay a 1080ti that had the G12 adaptor and a corsair H55 attached to it.

Looking at the the new gpu it doesn't have any of the fans connected to the gpu board (H55 aio fan or the small NZXT fan attached to the board). I've managed to give power to everything via my motherboard chassis 4 pin - which has a 1 to 5 4 pin adaptor, but the gpu believes it's fans aren't running at all (guessing due to nothing being connected). In addition to this the fans for this gpu are running all the time but I'd like to shut them off at idle or atleast be able to control them via my gpu temps software.

I'm planning to replace the H55 with a supported 240mm aio so I can run the fans lower and hopefully get rid of the old pumps loud coil whine. But before doing something that might now work I wanted to confirm what the best approach is to connect everything up.

At current I have a 240mm aio used by my CPU which uses my motherboards onboard USB 2.0 header, the aio 4 pin header and the CPU 4 pin header (using the Y cable provided by corsair to power both fans).

So questions:

• If I were to connect a newer model 240mm aio to the G12 am I correct thinking I can attach the USB 2.0 header to my USB 3.0 header on the motherboard, using an adaptor?
  
• From there can I power the pump via my chassis 1to5 4 pin adaptor and plug the 2 aio fans into the GPU (as there are 2 3 pin headers) or should these also just remain plugged into the 1to5 adaptor, whilst the G12 fan is plugged into the board?
  
• Finally would I need to use the small G12 fan that's been provided, given my ITX case has the GPU pretty low to the case base and I could have a 120mm fan applied to the case base pulling air in and onto the GPU, which I'd assume would be quieter and more efficient than running a small fan?

 

[Guptilious]

When I had my G12 I bought an adaptor to join the 120mm fans from the AIO to the card so I could control it via afterburner. The small fan on the G12 does the job of cooling the VRM. I would keep it on. you can always change it to a quieter one. I put a noctua one on mine but would go for one of the Arctic P9 fans to fit.

Did you also decide to attach the 90mm fan to the card or did you opt for running it into the motherboard. I've got a Noctua NF-B9 kicking around so was thinking to replace the stock one with this.

 

[Guptilious]

ran the small fan off the mobo at a constant speed

Awesome thanks for the help, I've got everything installed and configured how you suggested and I've got the fan speeds appearing now for my GPU. I installed 2 NF-F12's on the radiator and I had to buy an adapter as I didn't realise the GPU header was different.

An issue I'm now encountering is that I can't seem to drop my RPM below 1000RPM but I can increase them (regarless of if I try the stock fans, a notua Y cable or the stock one included).
Do you know if you have similar issues with your set up or if maybe the adapter I got could prevent me from being able to drop things lower and quieter?

 

[Guptilious]

My fans did stop when the temp was low but I adjusted them to be on low because I didn't want the coolant temp to be high. My fans went down to 200rpm at their lowest.

Weird. Don't suppose you have the link to the adapter that you used for your build? Might be an option for me to try out, as the noctua fans should be capable of going as low as 300RPM.

 

[Guptilious]

If I were you I'd simply ensure the pump is on full and the fans are set to an inaudible level via the motherboard connectors (so long as this cools sufficiently). Then just leave them alone. A 240mm radiator is far more cooling than a 1080ti needs unless you're trying to break world records.

Interesting, any reason why you'd have the pump on full? I found the sound from the pump in the current set up is quite annoying myself, so preferred to have it in the silent mode, with the aim of the fans also being low. I agree that the 240mm is overkill but I found the tube length on the H55 caused some issues with tubes being 'bent' together so I was more concerned by the water not flowing around.

If the fan connect replacement doesn't solve the adjustment issue I will probably go the route your suggesting and control everything via the motherboard connectors.