Looking for some help on my older, but remarkably stable desktop.  Last night it was working fine, this morning not so much.  Nothing unusual has happened (power surges, knocking the case over, spills, etc).  Have performed a couple reboots and PSU power drains but cannot get any video output.
 
Cracked the case (and had to take out a video card to get to it) and watched POST codes, appears to get stuck on either b7 or 67, not sure which.  Probably showing it badly here, but the very top line segment on the left character is missing, guess that makes it a 'b'?  Only takes ~3 seconds from hitting power button to getting to this POST code.
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So far, I have taken out RAM in slots 3&4 with same result.  Same as just running a stick in slot 1.  Flipping the BIOS select switch seems to have no effect.  I had it in the right position, but either way still getting the same POST code.
 
Anyone have an idea of what to try next?  Any input would be helpful :)

X79 FTW manual PDF
 
post codes p27
 
 
63-67 CPU DXE initialization is started

Place GPU in a different slot ? so you can still see the POST display
 
bad Coin Cell battery ?

rjohnson11
The easiest thing to try first is another DP or HDMI cable. If your video card has an HDMI connection and your TV at home has an HDMI cable 'borrow' the TV HDMI cable to see if that works.

rjohnson11, it is not even getting past the POST so I can't think of why changing the monitor cable would help.  For humor's sake, I did unattach both DVI monitors and tried a single in HDMI, same POST code where it stops.

Cool GTX
X79 FTW manual PDF
post codes p27
63-67 CPU DXE initialization is started

Cool GTX
Place GPU in a different slot ? so you can still see the POST display
bad Coin Cell battery ?

Cool GTX, is this POST code b7 or 67?  Either way, I've checked the same manual as well and could not decipher what either one means.
B7: Configuration Reset (reset of NVRAM settings)
67: CPU DXE initialization is started

For the GPUs, I've tried with both, with either one by itself, and with none.  Same POST code each time.
For the coin battery, I could certainly replace that.  Easy to get to now that the GPUs are out :)

bcavnaugh
How old is the Power Supply?
Recheck all the Power Cables on the MB side and the PSU Side.
Pull the CPU and check for Bent CPU Socket Pins.

bcavnaugh, the power supply is original to the build, a Seasonic SS-1000XP 1000W.  Maybe 7-8 years old at this point?  I have checked and re-seated the pair of CPU power connectors and the 24-pin connector.  Everything looks ok with them.  For the CPU, I am very hesitant to pull up the heat sink and look at it.  Usually like planing them at the time of build and never touching again, though it may come down to this...

KenMcC
bad CMOS (coin cell) battery IMO would be easiest too check as your mob is at least 3-5 years old.  Next, probably silly by me, would be moving video card to different slot

KenMcC, Cool GTX had the same idea about the coin battery, I'm going to be running out to get a replacement now.  Also tried moving the GPUs around and even taking them both out, same POST code no matter which way I tried.

Found this post   RAM issue

Critical errors: Error 6b and error 67 - SOLVED

Keep Us up to date on your Progress
 
Mods - do Not Close Threads, unless the OP asks it to be closed - or - there is a major TOS issue
 
GL

Cool, so I've got new DIMMs that appear to be working, but now getting a message after the x79 splash screen, 'Missing operating system'.
 
I've got 4 hard drives: 2 SSD and 2 spinning disk.  The two SSDs are RAID1 and contain the OS, and the two SATA drives are also RAID1 and are primary storage.  Within the BIOS -> Advanced -> SATA Configuration, all of the drives are listed as disabled.  SATA mode is also set to 'AHCI mode'.  Should I enable the drives here, or is there a separate RAID controller during bootup I should be getting into?  The support manual doesn't seem to give a clue one way or the other.
 
Thanks, making progress!

Success!!  So all I did was in the BIOS Sata Configuration screen, set it to RAID and enable the SATA ports 1-6.  Save, exit, reboot.  On next boot, went into the RAID controller settings and it detected both RAID setups right away, didn't even need to change anything.  Power off, put everything back in where it should go, and BAM OS boots right up with the new memory.
 
BIG THANKS to everyone on the thread!
 
Can mark this one as solved, ended up being a bad DIMM.