Dual Xeon / NCCH-DL trouble

All of a sudden the system is POSTing with the message "system boot fail. maybe overclocked, load default." After which we can press del for bios setup or hit f1 to continue booting which works!? However every few weeks this turns into "cmos ROM error/corrupt" and no POST anymore. We have checked everything, every setting and voltage/timing/multi etc. re-flashed the latest BIOS to be sure but still it turns up again. The system is (and always has been) running two Irwindale 3.2Ghz xeons at stock speed, could the mobo be dying?! PSU is a certified Enermax 660W EPS with quad +12V rails...

Well it seams that you are doing all the right steps. I run dual xeons on the PCDL. Sure you have, but will throw out that you replace the CMOS battery. Also check your cooling, possible related to heat, clean and reseat the HSF(s). These of course all just based on things I have seen that may or may not be your problem. One thing for sure if you are under warranty ASUS will RMA that board and then you will know.

Cooling isn't an issue. The system is watercooled by two Swiftech MCW6002 blocks with Arctic Silver 5 TIM. Those copper blocks alone should give sufficient cooling to make it into Windows...

I agree with trying to replace the CMOS battery first. I run PCDLs 24/7 hard for about a year now & no BIOS problems so far.

Yea my system is also on H20, massive blocks, huge metal fans, MAG 5, outside box and all that. Running my 2.4s at 3.5 stable all year. Got 2 units on H20 here, vmods and extra cooling all over and still I run the basics first when looking at corrupted bios. Since you are getting the OC error and everything else seems Ok I would just give the blocks a peek, lots of tork on these dualies with big blocks and tubes full of liquid you could have a contact issue or even a bit of warping on the board. But again I'm just guessing here. But I try just about everything before I go and say it must be the board and it usually isn't.

One issue we tackled so far is that the 2-2-2-6 HyperX RAM in the system needs at least 2.65V while the BIOS defaults to 2.5/2.55V. On top of that SPD gets interpreted incorrectly so the wrong timings are set! After correcting this the system passes POST considerably faster and runs 24/7 stable again but the "maybe overclocked" message still needs to be bypassed on every reboot...

Is anyone running any Beta-BIOS for the NCCH-DL and has positive experiences with it?

Can you set the bios to not halt on errors and not see this, is that a fix?

Also I do recall having problems/error reporting on my PCDL when I set up the H2O. The onboard fan RPM monitoring for the CPU's were falsely alerting since I went to water and did not use the fan heads. Might want to check that.