Hi (sorry for my english),
 
i had the same problem. My mb booted loop every time and the last mb code was 68.
 
I solved this issue with disconnecting the two 6 pins pcie wire from psu on my 8800gtx (still works fine ^^) and the 8 pins wire for processor.
i boot without this 3 wire and the mobo display FF code and my video cards whistled.
After, i repluged all wire and the pc started fine ..... after i updated my bios to version 83 and it still works since 2 weeks.
 
hope it can help

I'm very disappointed to report I'm now suffering a similar boot loop issue. although my system is throwing up only F3/F6
however it does not always reboot it just sits there and waits fro the rest of the post gear to happen which of course doesn't and it just sits there apparently hanging.... when it does that it seems to display a code 08/80 not sure which.

this has only happened suddenly too. has been working perfectly up until now...

Are you guys running oc'd?

Has anybody a solution for this problem?

I have the same issue - just recently happened. Unfortunately, the board is out of warranty and I am not in a position to build a new system. I am seriously considering selling off all the parts and calling it a day. Very depressed about this - was such a good system for many years.
 Let us have a moment of silence for my dear departed system {insert TAPS here}

Do any one of you that is having the boot loop issue with a f3, f6 code have a another cpu to try?

It has been my experience that the f3 f6 boot loop is related to memory.  Please remove all memory sticks from the motherboard and power it on.  It should give you an error code of 7F.  This would be normal.  If you still get the f3 f6 loop with no Ram installed then it is likely a memory controller issue.  The memory controller for all X58 motherboards is in the CPU.  If you get the 7F code then it is a memory issue and you need to test each stick of ram individually.  You may also want to try setting your ram timings in the bios to what your ram manufacturer recommends.
 

I had this problem on a computer I have been using a couple years. Everything was working fine, then one day turn it and got F3 F6 F3 F6 68 pause 69 then reboot loop. Long story short, removed all ram got F3 F6 F3 F6 flashed 62 and reboot. I did try re-seating the CPU. A friend had an I7-920 I borrowed to test the motherboard. It was the CPU in the end.

I too have joined this club with my x58, this afternoon playing on it and it just reset, then would not boot giving the F3 F6 then a few more codes then 7F.
 
I have opened a support ticket with a EVGA tech and am working it, but I'd like anyone here to watch this boot and give me their thoughts as well, I videoed it booting before troubleshooting and uploaded that to my own website:
 
http://www.dynamicflight.com/dl/EVGA Boot Up.mp4
 
It's somewhat bittersweet, I just got the system upgraded to win 10 and it was humming along nicely, I'd had no issues with it for 6 years.
If indeed the processor, I may get a refurb i7-950 instead of a 920 to allow me to run it without OC'ing. (my OC was very mild as well, nothing that I believe would have contributed to it, I only say that because it was in that config for 6 years, and had been cleaned out every quarter, no dust on anything ...
 
I appreciate any responses beforehand, thanks.

HRPuffnstuff
Are you guys running oc'd?

yes, being a 980x it was only a light OC to 4ghz.