iMac 2015 5K - fan noise

I’ve moved onto iMac from using a desktop and notice there’s a general fan noise constantly when using Cubase 8. I this normnal when using Cubase and I just need to get used to it? Notice that the fan doesnt really whir like that when using Final Cut Pro X? I am streaming audio via thunderbolt exterbal caddy (which has SSD drives, could that account for constant fan noise).