GPU in SLI, one card's fans are spinning and the other's isn't

Waynechang92

Commendable
Jul 20, 2016
14
0
1,510
So after RMAing my mobo I recently completed my build. However one card's fans are spinning at 1k rpm, and the other's are at 0. I checked the physical cards and the top card is the one spinning and the bottom isn't. Both temps are ~30C. Is this a faulty card or is this supposed to happen?

PCPartPicker part list: http://pcpartpicker.com/list/VWFyKZ
Price breakdown by merchant: http://pcpartpicker.com/list/VWFyKZ/by_merchant/

CPU: Intel Core i7-6700K 4.0GHz Quad-Core Processor ($324.99 @ SuperBiiz)
CPU Cooler: Corsair H115i 104.7 CFM Liquid CPU Cooler ($114.99 @ Newegg)
Motherboard: Asus MAXIMUS VIII HERO ATX LGA1151 Motherboard ($204.99 @ SuperBiiz)
Memory: G.Skill Ripjaws V Series 16GB (2 x 8GB) DDR4-2400 Memory ($64.99 @ Newegg)
Memory: G.Skill Ripjaws V Series 16GB (2 x 8GB) DDR4-2400 Memory ($64.99 @ Newegg)
Storage: Samsung 950 PRO 256GB M.2-2280 Solid State Drive ($186.99 @ SuperBiiz)
Storage: Samsung 850 EVO-Series 500GB 2.5" Solid State Drive ($156.44 @ Amazon)
Video Card: EVGA GeForce GTX 1080 8GB FTW Gaming ACX 3.0 Video Card (2-Way SLI) ($679.99 @ B&H)
Video Card: EVGA GeForce GTX 1080 8GB FTW Gaming ACX 3.0 Video Card (2-Way SLI) ($679.99 @ B&H)
Case: NZXT Phantom 530 (Black) ATX Full Tower Case ($120.99 @ SuperBiiz)
Power Supply: EVGA 850W 80+ Gold Certified Fully-Modular ATX Power Supply ($119.99 @ Newegg)
Monitor: Asus PG279Q ROG Swift 27.0" 165Hz Monitor ($799.00 @ B&H)
Total: $3518.34
Prices include shipping, taxes, and discounts when available
Generated by PCPartPicker 2016-08-31 13:28 EDT-0400
 
Solution
If you are not playing a game I believe SLI is set up to power down the second card to a low power state since its not actually doing anything.

Check the fan operation when a game or benchmark is running to confirm.
Are you sure you have SLI enabled in the Nvidia control panel? My GTX 1080's fans stop spinning once the temps go under 50c I think. Your card might be like that except make the fan profile is a little different on the other card. Try putting a load on the GPU and see if it ever spins.