verify with your users manual that you have it in the correct slot, that you have the correct power going to it, are using the cables from the correct PSU (if this is a modular. Cables are not generally interchangeable).
If you have the rampage motherbd, did you plug in the extra 4 pin power connector that by the motherbds 8pin cpu power?
Please list/link your builds specs. Thanks.
edit How sure are you that its the VGA led? I dont know of an asus x99 bd that has that, I thought they all had the q-code leds and a dram led.