ECC RAM isn't required to boot. But if you aren't using ECC you are basically implying that you are using desktop parts. By saying you are using desktop parts you are also saying that it might not boot FreeNAS, it might boot and crash, or other things that just don't happen to "everyone else".
You are literally on an island by yourself with nobody to support you because those of us with experience in FreeNAS use proper hardware. That means server-grade and ECC RAM. ;)
I'd bet money your problem is that you are using desktop hardware when that's not recommended or supported by FreeNAS. :p
Very much people attitude about Windows vs. NIX, Intel vs. APPLE, ECC vs. non ECC RAM, nuclear vs charcoal powerplant, race car vs sedan and so on and on.
Granted server grade is by definition supposed to be more reliable but definitely not fail/compatible proof, otherwise every single ECC-RAM manufacturer and Motherboard would guaranty full compatibility.
The way I see it, a server is designed to take on limited function such as Web server, firewall, files erver. So they are tested hopefully to death in a very specific environment and with very specific hardware. Beyond that, well I would say you are on your own.
Also, it seems server grade hardware will get full support if you buy hardware for a business, not for home use.
I wouldn't expect to find server grade system for the ISS or spacecrafts and satellites going into space. Definitely server grade is not going to perform any better than desktop computers. You will need harden hardware for that.
I noticed there always is animosity and discord on both side on the barrier due to divergence of opinions.