Alright,
 
So my machine had a couple of bad boots yesterday, it'd get stuck mostly at code 66, but eventually once it booted it was fine.
I ram memtest overnight (thinking it might have been memory or something), it completed multiple passes without a single error.
 
I used my machine this morning, no problems, went off to uni, came back and pressed the power button and did the usual just-got-home stuff while it goes through its 15 second post and whatnot.
Sat down to actually use it, and the screen was still off. I peeked inside the panel expecting to see a code 66, instead, it was a code "C". I've checked the manuals and cannot find anything about this post code. What's more is the board no longer does anything when it's turned on except turn the fans to 100% and show the C - nothing else shows up, as soon as the button is pressed, just "C".
 
What can be done?
 
I've tried the usual, reseat memory, reseat CPU, reseat all power connectors, swapped GPU, tried with 1 memory module in different slots, nothing changes the fact it just says "C" on the post LED thingy.
I even tried without CPU/GPU/RAM and with/without the EPS power connector plugged in, exactly the same outcome - "C" on the little display -_- 
 
Any ideas? Or is it RMA time?
 
Cheers in advance

EVGATech_GabrielT
Dear ValkyrieStar,
 
 
Issues like this would commonly indicate that the motherboard or PSU has failed. If you have access to another PSU I would test this. If the issue persist the board would need to be replaced. 

I shall try another PSU.
 
I'm unsure if it would be the PSU anyway, as I commonly game and do other pretty intensive things on there, so i'd have expected it to have failed under load. I'll try it anyway :)

I wonder if your Unofficial X99 BIOS Update has anything to do with this.

Remove the CPU and look for Bent CPU Socket Pins!

just had same issue ran on 1.03 for 5 years, evga sent me a new bios to physically replace and update bios, now posts only c. Swapped in old bios posts to c. Seems like new bios killed board. Nothing works evga directed me through the process as I was doing it. Made sure orientation was right I have pictures to prove it is the same. Board dead.  I feel like since they were on the phone directing me while it happens they should take some responsibility. Evga says past warranty, sorry for following our instructions but seems like board is now dead. Why would they send me a bios that killed my motherboard, now my functioning computer is dead. I did this to add memory so I can replace my 5 year old sticks, the newer bios 1.19 added support to the newer memory. If more than one person is having a c post when upgrading from 1.03 to newer bios it seems like maybe this is actually a bios issue on evga's side that they should be aware of, but because the mobo is over 5 years old all they can do is apologize and say I should try buying a board on ebay or force me to buy a whole new computer this is really just absurd.