I used to write BIOSes for a living and I'm still involved in that business but don't get to do a lot of interesting coding any more.
Answering the answer: why would I want to buy an expensive motherboard with limited PCI-e expansion capability for a workstation? When better hardware is available much cheaper? I think the answer is obvious. It is to me. I want the best hardware for my software development. And the server board benefits (an iBMC and support for remote management) don't seem worth much to me in my circumstances.
Yet I know 16 GB of non-ECC memory (my target configuration) is going to generate panics and corrupted sectors on my hard drives pretty regularly. Numbers like one memory failure every few days seems pretty common in articles on the web discussing systems with that amount of RAM.
With 16 GB of non-ECC memory in this motherboard I am seeing 2-3 failures per week running a stock memory diagnostic (I've not been able to test the ECC configuration, of course, but I would expect the failure probability to drop to virtually 0 if I required 2 of those 3 failures to occur in the same 64-bit word).
That seems pretty much what I should expect, and is enough of a problem for me that I'm willing to put some coding effort into eliminating the problem.
I also don't want to just fly off and do a hack on my own if someone else has already done some investigation of the situation. Unfortunately, I don't know enough people who have hacked BIOSes to have personal connections. Thus the question.
But if I am the only one looking at the problem, I am a bit surprised, but I don't mind digging further into hacking a BIOS. It may or may not be worth the trouble.
That's why I put the question in a programming question area, not an admin area. This does require changing the BIOS code (I would be very surprised if it did not, quite frankly).
I am fairly confident that the system hardware (with the possible exception of missing 8 or 16 wires for the 8 parity bits) is capable of running in full ECC mode - the processor includes an ECC capable memory controller, the DIMMs are unbuffered ECC DIMMs with the same electrical requirements unbuffered non-ECC DIMMs have, so the only motherboard feature involved is the set of wires and passive components that connect the two.
And in response to the comment that 85% of consumer boards will fail to boot with ECC: my experience is in the same ball park. Without modifying the contents of the SPD EEPROMs on the DIMMs, EVERY consumer board I have booted fails to boot with ECC DIMMs installed (all were DDR and DDR2 boards, not DDR3, though). However, with hacked ECC DIMMs, every one of them did boot successfully and the ones I ran memory diags on all ran for days with no errors. So the failure to boot is a decision made by the motherboard firmware/BIOS or something else that reads the SPD EEPROM contents.
WRT the note about the failure sequence making sense: what bothers me is that I see NO indication that the BIOS is following that sequence. It appears to be testing for validly installed ECC DIMMs first (since I see no PORT80 codes displayed in the case of the validly installed ECC DIMMs), then does some other stuff (several PORT80 codes) and finally reports the invalidly installed ECC DIMMs are not installed in the correct slots.
I actually find this promising since it makes me think there may be an explicit test for ECC DIMMs executed early in POST (possibly to prevent the system from running with a Xeon processor and ECC DIMMs).