Hello,
I'm starting a dedicated thread since the other threads I've requested information regarding this topic seem to be a bit too spread in their discussion, and this topic didn't seem to garner any responses.  I need to be a little aggressive on the topic since my client's project is time dependent, and I need to get something up and running as my current machine is suffering some power issues. I'm hoping for some response from EVGA.  Nothing I will hold them to, only their feeling based on their experience.  I know you (EVGA) can't guarantee anything that hasn't been thoroughly tested by your company.  I'm just looking for some professional judgement, whether it turns out to be right or wrong.
 
Just to be clear, I'm not looking for a dedicated or cheap server option.  I'm looking at the x99 EVGA board with a Xeon processor, because it does have some consumer features, but not so many as to be beyond my current/future needs.
 
I'm tempted to test some Unbuffered ECC memory, but the cost to do so is rather high.  I've located some Kingston unbuffered ECC memory that is a potential option, but I don't want to commit to 4 sticks for testing at that price if I don't need to.  My questions are:
1) Can I test with only 2 unbuffered 16GB ECC RAM sticks, or do four slots have to be populated.
2) If two sticks post, is it highly likely that increasing to 4 or 8 slots will work (64GB / max 128GB).
3) Where can I purchase unbuffered ECC RAM (some of the usual suspects like Amazon, NCIX, etc., seam quite low on stock and may not have additional sticks after I've tested the first two). How about Memory America.  Anyone have experience with them?
4) I've just learned that ECC memory and non-ECC memory can be mixed.  Apparently, ECC memory will act as non-ECC memory in these cases.  I am wondering if ECC memory that didn't work/post alone would become functional if mixed with non-ECC memory.  That would curb some of the lost cost if the 2 sticks of ECC memory didn't work.
 
I will use this computer for some entertainment purposes, but also as a work computer. The type of work I do may require 6 or more hours to process a single run.  Maybe much more.  So, crashes of my computer during these runs, especially when I'm working against a tight deadline, can be costly.  Having 128GB RAM seams to mean the chances of errors will increase with the increased ram.
 
I can discuss other builds or options in the other threads I've posted in.  I would like to keep this thread focused on the questions above. 
 
Thanks,
Dave

Thank you Bill for your response and links.  I've added a fourth point in my list above since you posted your help, and also found Memory America which I added to my third point.  Memory America apparently has a 30 day return period.
 
I'm not an IT person, so I'll admit some naivete when reading your response.  Specifically, does ECC require memory mirroring?  Everything I could find on the topic seemed to treat them as separate topics. If ECC does require memory mirroring, then I'm guessing you are suggesting my chances of the un-buffered ECC RAM working are slim. I thought, probably erroneously, ECC redundancy was mostly processor dependent for doing the error checking. If I understand what you say above, then I would hope EVGA would be able to state almost wholeheartedly that ECC will not work due to no redundancy/mirrored support in their BIOS. (By the way, are you from EVGA?).
 
-Like you, I don't plan to touch overclocking. Stability is more important for me.
-I'm not sure how the software manages checkpoints.  My experience in the past with similar software was that a memory error usually lead to the program shutting down/crashing. Visual Modflow doing contaminant transport modelling seemed to plague me with errors, which if my memory serves me well usually noted a memory address. That was on an older ASUS board. Currently I am using an ASUS P8Z77 premium board to run Feflow software which is a more powerful version of the Visual Modflow software, and hopefully more reliable. However, I've already seen it crash a couple times on my current computer, and have only run it half a dozen times since purchase.
 
To answer your last question: I use the above noted software to do groundwater modelling which is quite computationally intensive both in the setup of the mesh, dual precision calculations, and finite element modelling.
 
Thanks again for your comments so far. Hopefully my posts will get a little shorter as I start to understand the issues you have noted.
Regards,
Dave

Dave, to reach an EVGA tech rep, I would just call them since they're open 24/7.
 
Also, if you are willing to wait this out, the new X chipset is a few months away.  I would personally wait for that.

I can't say too much but all I can say is this.  When new features come out, yes there are bugs to be fixed.  We had issues with M.2 being somewhat new at the time as there were fixes to be had.  Depending what he X299 offers, if there's nothing new but tweaks from X99, I think it will be fine.  
 
The other thing I can say is, verifying that said Xenon will work with said board.  That can take time and possibly a BIOS update but we aren't even sure as of yet but history has shown, that Xeon's usually work with these type of boards.
 
I personally would go with the newer chipset because I like to have the newest if I were to purchase something of the same price point, knowing its around the corner.  I would patiently wait for May 30 - June 4 for Computex as there's a lot of chatter from AMD and Intel based on GPUs, CPUs and the new X MBs from both.  If you can't wait that long, than X99 it is.

"(By the way, are you from EVGA?)" No I am not.
This is not really an EVGA Support Forum but an Open Public Forum.
But EVGA Techs do post and answer members questions here on the Forum.
Best ask here:

• EVGA Support Team

• Contact Customer Service
• Email Customer Service

My thoughts:
 
1) EVGA would probably only tell you if they have tested any ECC RAM and not theorize if it is possibly possible.
 
2) Look in this part of the Forums - https://forums.evga.com/CrunchingEVGA-f79.aspx
     Many of these members have CPU intensive experience.
 
3) Would a dual CPU MB be better and it would have native ECC support ?
 
4) Contact RAM Mfg and ask them if they have tested ECC RAM in the MB you are considering