So .....
Apologies EVGA, the x299 Dark baseplate with visual aids holds the key. It has a nice legend for all the leds in that area.
Turns out it's not 5v standby power led but VCC led.
All this has been covered (several times ....
oops) in these forums. Just did not show up when searching for topics.
Very nice led summary here
https://forums.evga.com/FindPost/2813321 Can someone, lock this post and put it in the bin please?
