Does anyone know what the slowest fan speed is? Cause at low percents my fans aren't spinning even though they should according to the custom fan curve. And in the RPM.. meter or whatever it's called it said the fans were spinning at a certain RPM while the fans were actually just sitting there stuttering.
I just changed the fan curve just slightly on the low end and now i'm on about 5C lower idle temps. Which i'm assuming is cause that now the fans are actually spinning rather than just sitting there humping the card

Muske
It's around 35-40%. Any lower and the fans won't get enough volts to fully spin. Also keep in mind that you need Precision X or whatever software you're using to remain open if you want to use a custom fan curve otherwise it will use a preset one on the gpu (which doesn't spin the fans until 60 C)

Is it enough having "Start Up" in PrecisionX OC checked?
Here is my old vs my new fan curve. In the new one the fans are always spinning, even if i put my finger in one it'll start itself back up after a few seconds. On the old curve i got down to 36-38C and then sometimes the fans stopped. On the new curve it gets down to 32-33C and the fans never stop.

Currently i'm only using the stock Define R5 fans Dynamic GP-14 (68.4 cfm), one in the back and one in the upper front slot.
But tomorrow i'm recieving a Venturi HF-12 (83.4 cfm) and a Venturi HF-14 (118.2 cfm). I Plan on putting the HF-12 in the middle of the bottom which is basically straight below one of the GPU fans. And the HF-14 in the upper front slot while moving the GP-14 down to the lower front slot.
I was gonna get 2 HF-14's, but the PSU is too long so only a 120mm will fit in the slot below the GPU. Oh and i also got a fan grill for the HF-12 just in case, so i won't risk getting cables in it.
Hopefully this will take care of my current temperature issues on the high end. Which is that my stresstest/benchmark temps are better with an open side panel than having it closed.
And uh, sorry that i stepped in on a little side track here :^)

Question: is it really a problem for the fans not to be running if the temperature were low enough? I'm not sure I see why that's a bad thing*. If you're just browsing the web in Windows, the gpu isn't doing much, and probably doesn't need the fans going.
 
*if you're trying to undervolt the fans to the point that they're trying to run but stuttering, that could be an issue, but just turning them off completely at low temps shouldn't be a problem.