Not possible, your use of the second M.2 slot has disabled that PCIe slot. Best you could do would be to install the sound card in the other x16 slot, which would drop your GPU down to 8x.
- 1 x PCI Express x16 slot, running at x16 (PCIEX16)*
- Actual support may vary by CPU.
- For optimum performance, if only one PCI Express graphics card is to be installed, be sure to install it in the PCIEX16 slot.
- 1 x PCI Express x16 slot, running at x8 (PCIEX8)*
- Actual support may vary by CPU.
- The PCIEX8 slot shares bandwidth with the PCIEX16 slot. When the PCIEX8 slot is populated, the PCIEX16 slot operates at up to x8 mode.
(The PCIEX16 and PCIEX8 slots conform to PCI Express 3.0 standard.)
- 1 x PCI Express x16 slot, running at x4 (PCIEX4)
* The PCIEX4 slot shares bandwidth with the M2B_SOCKET connector. The PCIEX4 slot becomes unavailable when a device is installed in the M2B_SOCKET connector.
- 2 x PCI Express x1 slots
(The PCIEX4 and PCI Express x1 slots conform to PCI Express 2.0 standard.)
Not sure you have the name of sound card correct. What is the exact model? The motherboard has a fine audio chip that should be fairly well isolated from the GPU.
- Realtek® ALC1220-VB codec
- High Definition Audio
- 2/4/5.1/7.1-channel
- Support for S/PDIF Out
I myself used to find sound cards necessary due to interference from GPUs, (and a hard drive once) with onboard audio. But the last few generations of hardware they've pretty much made it industry standard to have good isolation and even decent amplifiers on the high end boards (the really high end ones have sockets for amps)
If you are using some advanced features on that card, then you'll have to wait for an audiophile to chime in. Though these days I understand external sound devices and DACs are more popular.