Mine failed too on my Z590 Dark.
 
It's not a deal breaker, but, kind of a bummer.  It's a very useful feature when it works.  Also bad on an X299 Dark I bought, but, I think the PCB is slightly bent in that area so that's not the boards fault.

Apollo1321
I finally put together my z590 dark after rma'ing the first one for the post code leds, they sent me a sealed new replacement. But it sat in its box until two weeks ago. The leds have failed within two weeks of use, again. It also has a weird problem if i set static fan speeds the board just randomly decides there is no fan attached at all and stops them. It actually overheated my gpu loop before i noticed that ALL the fans on gpu loop werent spinning. Cpu loop fans were tho. I also see that they never fixed the cpu speed cap of 5.2ghz in the eleet x1 app. Z590 Dark has been the worst board ive ever used. Doesnt help that evga abandoned it really quick for z690.

If you have a repeat failure please contact EVGA tech support. 

Same problem on my X570 FTW, the left digit went dim (but not all the parts) It can display 4 but not 3,5 etc... shouldn't happen with a board this expensive. Do they even have a spare?

 
Honestly not sure if this is a sign of my post LED failing on my x570 dark, but extra digits are being rendered on the 2nd POST segmented display. Only noticed this after rebuilding my pc with a new case that uses a glass side panel (beforehand I was using a full metal case). This only happens for certain digits, so i dont think its worth RMA'ing yet, sure do hope I'm still under warrenty when this fail, if it does. Its wonky behavior IMO for a POST light, but then again, this is the first time I've ever seen a 4 digit - 8 segment display on a motherboard. Aslong nothing's shorting I'm happy . 
 
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