Using more than two monitors causes 20°C higher idle temperature

Hello everyone,

I’m using a three-monitor setup on my GTX 780 Ti (DVI, DVI, HDMI). Driver version is 334.21, 64-bit, Kernel 3.13.6 (Arch Linux).

Compared to using only single or dual monitors, the performance is perfectly comparable; for instance Heaven Benchmark yields similar results.

However, I noticed that there is quite a huge difference regarding the idle temperature. When using a single or dual monitor setup (using any combination of ports), the numbers are

38°C, 1130 fan rpm, 26% fan speed.

Now when I’m using three monitors, the idle temp is significantly higher:

58°C, 1560 fan rpm, 37% fan speed.

How can this 20°C difference be explained? Is anyone else seeing a similar behavior?