I installed the 120mm CLC, the USB cable is hooked up to my motherboard USB 2.0 header but every time I start up the flow control software it can't find my cooler, in the devices it says "Unknown USB (Device Descriptor Request Failed)"

My motherboard is ASRock Z170M-ITX/ac

i had the same problem, fixed by removing corsair link usb header from my power supply.  

when i open the software it said device not found and closes.  when i double click again it software runs but only reads cpu temperature, nothing else.  so i removed the corsair link usb header that goes from the powersupply to motherboard, and uninstall corsair link software completely in windows, now it reads everything fine.  

I also had this issue.  I found it happening only when I was overclocking to my limits (sitting at 5 gHz) by using the Asus 5-Way Optimization. As soon as I remove this level of overclocking (still overclocked, but reduced it a bit), the cooler was found again by the software. Weird.
*I also tried restarts, shutting down and moving the USB to different ports (I use a NZXT internal hub) - made no difference, still device not found. 
 
Asus Maximus IX Code
i7-7700k w/ EVGA CLC280
EVGA 1070 FTW Hybrid
32gig DDR4 3200 Geil
EVGA Nex650 PSU

For those of you who have this problem but don't have any Corsair software installed please contact EVGA Tech support.

SoCalGamer86
I installed the 120mm CLC, the USB cable is hooked up to my motherboard USB 2.0 header but every time I start up the flow control software it can't find my cooler, in the devices it says "Unknown USB (Device Descriptor Request Failed)"

My motherboard is ASRock Z170M-ITX/ac

Sound like your Chipset Drivers need to be updated.
In your Device Manager do you have any Yellow ! showing?
You can also remove the USB cable from the CPU side and you should here the Windows Sound chime of a device was removed and then plug it back in.
If you here no sound Check in the Bios that you have Legacy USB Mode Enabled.
Do Not Do this on the USB Motherboard Header Side of the USB Cable.
 

As a last  idea before sending anything back
Connect the Cooler to a different computer USB - using a mini USB to USB cable.
Load the software on the second computer and test.
 
I also find if I have start with OS and start minimized OFF in settings things work better.
and you need to re-minimize and NOT click the X or you will have to re-boot.
 
And WinRing0
(

OpenLibSys Core SDK

WinRing0 library allows x86/x64 Windows applications to access
 - I/O port
 - MSR (Model-Specific Register)
 - PCI

) may cause some problems on some systems

Have you tried setting the CPU Fan Header (or whichever PWM header connected to the pump) in your BIOS to Max?  If left at Smart or auto, or something similar, it can cause this issue.  The pump/fan will still behave normally, but it can otherwise be undervolted if the header is not set to Max/100%.

Squall_Rinoa86

EVGATech_LeeM
Have you tried setting the CPU Fan Header (or whichever PWM header connected to the pump) in your BIOS to Max?  If left at Smart or auto, or something similar, it can cause this issue.  The pump/fan will still behave normally, but it can otherwise be undervolted if the header is not set to Max/100%.

I have the one that's labeled Motherboard on my CPU 4pin connector, even tho its only a 3pin.. other then that, USB mini is plugged in. I need a bigger case apparently cause I had to jerry rig the radiator to my CoolerMaster XM Case to fit it.. Seems i'm in the market again for ANOTHER case.

I've got the Corsair 780T case and it rocks. 

Glenda94
I have this same problem (device not found). It just disappeared when I  was testing my overclock temps in a render. My cpu hit 103 and I stopped the render, but could not resurrect the software. I'm going to try some of the above suggestions, but I wonder if it has to do with the motherboard (asus) 5 way optimizing your overclock. That software takes over the cpu fan control so there's 2 separate power management systems plus windows power management in the mix. I can't help but think this has something to do with it. I have no Corsair in  my system.

Yes, if you hit the optimize in the fan control software it will shut down your pump, it is testing its capabilities as a PWM pump which it is not. Even if you set the pump header in the BIOS (if your MOBO has one)  to DC 100% and then run the optimization- it will still test it as a PWM controllable pump. 

Did f5 in bios and the Evga cooler software is back. The water pump is working and being controlled by the software. The cpu fan is still being controlled from the asus fan optimization, but I tried an intense render and the cpu just hit 83, so I'm pretty happy.

just asking, did you install but not run the evga flow software BEFORE installation of the CLC ? i found for me that worked .I ended up RMA'ing my first 280CLC and did a clean uninstall ,rebooted,installed(with old cooler in place but not usb connected) then shut down ,swapped CLC's hooked USB up.Booted up .The first boot i made sure to tick the start with windows,+ minimized .CPU 1+2 fan headers set to full.Rebooted .On next start up program loaded,detected but no cpu temps (i almost died ) while pc was running pulled usb connection out waited 10 seconds (to cover any polling period) reconnected.Literally saw the CPU temp appear in Flow Control software .Since then 2 days has worked/loaded perfectly (except the pump slider always stays at 0.0% never adjusts with fans .Temps are acceptable ,have not tested with games or stress yet.Hope this might help anyone

BioHazardSperm
just asking, did you install but not run the evga flow software BEFORE installation of the CLC ? i found for me that worked .I ended up RMA'ing my first 280CLC and did a clean uninstall ,rebooted,installed(with old cooler in place but not usb connected) then shut down ,swapped CLC's hooked USB up.Booted up .The first boot i made sure to tick the start with windows,+ minimized .CPU 1+2 fan headers set to full.Rebooted .On next start up program loaded,detected but no cpu temps (i almost died ) while pc was running pulled usb connection out waited 10 seconds (to cover any polling period) reconnected.Literally saw the CPU temp appear in Flow Control software .Since then 2 days has worked/loaded perfectly (except the pump slider always stays at 0.0% never adjusts with fans .Temps are acceptable ,have not tested with games or stress yet.Hope this might help anyone

 
I was going to suggest that I found though sometimes  the bios needs tweeking too

Got same problem. The device not found appears after couple of hours working normally . Are the EVGA dev going to fix their damn drivers and this buggy software?

New version of Flow Control on downloads page as of 9/21/2017
Will try it this evening and see if it can display the CPU temps on my X370 board with Ryzen 1600 CPU