Hi,
I don't know much about your board as i have never used but i have just done some research and found you manual online.
If you can get in to the BIOS it says an option on the First Screen Half way down the page Drive A. If you High light that option it seems you can press the +/- signs to change its value to NONE or something along those lines. I believe you could also try pressing enter to it and see if it brings up a menu.
Make the change and Press F10 to save.
You view the manual i was looking at with the address below Page 29.
http://www.evga.com/support/manuals/123-YW-E175-A1.pdfHope this helps
Wayne