Shallowthought

Best thing to do is unplug one thing at a time. I would recommend unplugging all of your fans first. if you still hear it then it is coming from a hard drive. If not, you know it is a fan. From there you can narrow it down further.

I agree,  Noises are most of time fan noises gone south.  Like Votivee said liet us try to figure out which fan it is.  

are you definitely sure that applications are USING the gpu though? check that your video cables are in the gpu, you should also be able to disable the intel integrated graphics in device manager so only the graphics card is being used
also as everyone is saying, use DDU

Make sure your computer sees the new Video card. Sometimes they will default to the onboard intel video. 
(Right click desktop go to nvidia settings) see if the Nvidia video card is selected. 
 
Also Obligatory check drivers.