Best sound card position?

About a month ago I purchased an Asus Xonar DGX, but because of my setup (gpu and wifi card) I thought I had to swap my gpu from the upper pcie slot to the lower one. I know people run sli configurations with little room in between for air space, but I like having room and decent air flow for my graphics card. That being said, my card obviously got hotter and I'm trying to rearrange things if I can.

I've attached a photo of what the setup is like now
http/imgur.com/BWS9uNg

mobo: Asus z87 plus
gpu: Asus DirectCU II gtx 780 OC
wifi: TP-Link TL-WDN4800
soundcard: Asus Xonar DGX

I have the following slots available:
2 x PCIe 3.0/2.0 x16 (x16 or dual x8)
1 x PCIe 2.0 x16 (x2 mode)
2 x PCIe 2.0 x1
2 x PCI

I'm not sure about EMI interference and I was also worried about having the sound card too close to my gpu for heat purposes. The sound card is pcie compatible but I'm not sure if that means I can put it in the other x16 slot. Any help is greatly appreciated!

Edit:
Kept doing research on my own but wasn't understanding some of the info I found, but came across this site http/techreport.com/review/23624/how-to-build-a-pc-the-tech-report-guide/9 and decided to give this configuration a try. Gonna test it now but still open to other suggestions.