UnderwaterSurfer
I connected the stock radiator fan to my motherboard and controlled it using SpeedFan. A 2 pin connector allows one to use dc control, but without any rpm information. JayzTwoCents has a very good SpeedFan video:
How to set up SpeedFan - Free fan control software
 
I then replaced the stock fan with a Fractal Design Venturi HP-12 PWM Black Case Fan FD-FAN-VENT-HP12-PWM-BK. It is quieter and moves more air. I have 3 fans, including the radiator fan, controlled off of the GPU temp using SpeedFan.
 

Waiting for my 2 Hybrid kits from new egg. I also ordered a 2 pack of SP120 fans. I have 4 others in the case already. I would like to go push pull. I only have 2 PWM connections on my motherboard and would like to keep them solely for the CPU cooler. You mentioned that you use speed fan. I saw the Jayz video and tried speed fan but as far as I can see I can only control the PWM headers. Is there a way to control the other 3 pin fan headers using speed fan. I only saw setting for like 1-5 which I imagine are set speeds and will not adjust automatically with GPU temps.

Hi Mike,
 
Here are some images of my setup. They show the main page, Advanced tab, Fans tab, Speeds tab, Fan Control tab, and the Add Temperature in Fan Control. How many fan headers do you have on your motherboard? How are they being displayed in Speed Fan? I would think that all the fan headers can be controlled, but I am not sure. It seems that it depends on how they are being found and displayed in Speed Fan. Please provide some images.
 
 
  
 
  
 
  
 
 

Thanks for the Pics. What I am trying to figure out is if it is possible to set a curve on the 3 pin fans. You have your curve set to PWM 5. I would like to be able to set a curve on like lets say FAN 1 as Seen on the Configure page of your post. Those fans have values from 1-5 I believe. I assume that those values correlate to fan speeds. So I would like to be able to set fan speeds to GPU temp. Any one know if this is possible.

Some of my attached images weren't showing, so I put them elsewhere and have finished the original post with links to those images, so please look at it. The main question I have is about what you are seeing in the Advanced tab. Speed Fan is a free program that works great for me, but as Jay said it takes some time to figure it out for a particular motherboard.

In the Fan Control tab there is a drop down to the right of "Controlled speed". What is shown in that drop down? For me it is Pwm1 thru Pwm5, and each controls a fan header, but they are not named the same as what is printed on the motherboard. I tested each one to learn which header was being controlled. For me they are:
 
Pwm1 = CPU_FAN (controlled by Core 1 CPU temp)
Pwm2 = CPU_OPT (controlled by GPU temp)
Pwm3 = SYS_FAN2 (controlled by GPU temp)
Pwm4 = SYS_FAN3 (controlled by GPU temp)
Pwm5 = SYS_FAN1 (controlled by GPU temp)
 

Thanks again for the pics. I realized I'm not able to do what I wanted with the 3 pin. Good news is after reviewing my mobo manual I found another PWM on my board hidden by my RAM. Last question do I need to start speed fan every time I reboot my PC because I have not seen a setting for it to start with Windows.

I am happy you found the extra PWM! There is a nice video about starting SpeedFan on every boot, as there isn't a setting for that in the software. The only thing I don't do is set the delay time at all, as he shows at :55 in the video. It is slow to start anyway.
Tutorial: Auto-run SpeedFan on Startup - YouTube

I will receive my kit today for my EVGA GTX1080 SC ACX and have a question.
So, the fans are being temp controlled. For Founders Editions cards the two fans will always run and keep the card cool - I can imagine. 
BUT: on the ACX cards the fans are being turned off below 60°C - so, how will the kit work there? Do I have to flash another BIOS? Maybe the one for 08G-P4-5182-KR (1080 SC non-ACX)? I don't want to create a custom fan curve.

fubu1080
I will receive my kit today for my EVGA GTX1080 SC ACX and have a question.
So, the fans are being temp controlled. For Founders Editions cards the two fans will always run and keep the card cool - I can imagine. 
BUT: on the ACX cards the fans are being turned off below 60°C - so, how will the kit work there? Do I have to flash another BIOS? Maybe the one for 08G-P4-5182-KR (1080 SC non-ACX)? I don't want to create a custom fan curve.

Is the SC ACX even supported? But I bet your can create custom fan curves if you get it to fit, software can fix a lot.

I'm running push pull now on the radiator, been changing a lot and trying different combinations for fan set ups. Might be getting a $100 worth of corsair's new ML fan serie.

The Compatability tab at http://www.evga.com/Products/Product.aspx?pn=400-HY-5188-B1 shows all the supported cards, and the 08G-P4-6183-KR EVGA GeForce GTX 1080 SC GAMING ACX 3.0 is listed. EVGA has excellent support, and if your card is registered on their website you get 24/7 premium support. I have used it a few times and it is great! Call 1-888-881-EVGA (3842) ang go through the 3 menus entering 1 at all of them, and then enter the serial number of your registered card. They can answer all your questions.