fanchazstic

HBA - I currently have two of these. Whatever you get, just make sure it plays nicely with freenas. Freenas generally has pretty good support for hardware, but HBAs especially freenas can be pretty picky about.
 
HDDs - I don't know much about the Deskstars and don't own any HGST drives in general, but I have heard good things about HGST failure rates. Just make sure that whatever you get, it is designed for use in a NAS/server with tons of vibration from other drives and has TLER. 
 
That really sounds like a solid plan in my opinion. I can't think of anything that should be done differently.
 
One last thing, get a UPS if you don't have one. This is something that should go without saying, but especially for zfs, it is a must. Get one that can power the server long enough to shut down all the VMs with sufficient time left over to shut down the host OS. I have a CyberPower 1000VA pure sine wave that powers ONLY my server and networking gear. My desktop is on it's own separate UPS. Currently it estimates 17 minutes of runtime, which is way more than enough time to shut down the server properly. I like the CyberPower units because they are reasonably priced, replacement batteries are easy to find, and their PowerPanel Business Edition works with the consumer UPS models for shutting down ESXi (and it's free). But if you're just running linux, I'm sure there is support from most UPS models

if you're running freenas or zfs at all, get ecc ram. It is very important for the zfs filesystem. I am running freenas as a VM on my ESXi box with PCI passthrough with two HBA's. You can either get an old enterprise HBA and flash it to IT mode, or there are some relatively cheap sata HBA's on amazon that play nicely with freenas. That's what I've done and I can send you the link to the HBA's I use if you are interested in going that route. If this system is going to be important to you, go with raidz2. Raidz1 is safe, but rebuilding the array after one drive crashes puts the other drives under a heavy load and can cause another drive to die, therefore with a raidz1, you lost two drives and your data is gone. Raidz2 you can lose two drives and still be fine. It's a bit safer, but it's a tradeoff you can decide to make or not, but either way, you need to have backups. I'm not going to go on some rant about backups, you can make backups based on how you see fit, just make sure you are aware that raid is NOT a backup. As far as drives go, I only use WD drives. Seagate has been extremely unreliable for me over the years and I've had good luck with WD. Not everyone has the same experience, but there is a reason so many people over on r/datahoarder love the WD Reds. WD Reds are my recommendation. Stay far away from the seagate archive drives unless you fully understand what they are designed for. 
 
one more thing, your storage setup looks pretty solid, but if you want, you can use a share from freenas to store vms on. That way they are stored on a zfs volume that has some redundancy.  Depending on your budget, I would start small since you said you don't have much data to store yet. Maybe get lie 6 1TB or 2TB drives and put them in raidz2. That would give either 4TB or 8TB of usable space right now, and you can upgrade to 4TB drives or higher later on. But in order to upgrade a raidz2 pool, you have to increase the capacity of every drive in the pool. So you would have to replace all 6 drives with 6 higher capacity ones. But what you can do is take the old drives and turn them into another freenas box for backups of the more important data from the main server

I don't think he's saying that the model of PSU is an unreliable model, but that yours could be unreliable due to a failure internally. If there is a possibility that the PSU is causing your problems, updating the BIOS would not be a good idea. Since we haven't ruled out the PSU as a problem, and is actually suspect of being the problem, updating the BIOS would be a bad idea. So nothing against that model or brand PSU, it's just that sometimes things do fail. Another possible thing that could cause the issue is maybe with the motherboard. Maybe a trace is broken and makes intermittent contact. Maybe a heavier gpu places more strain on the place where it's broken and causes it to become unstable. But to be completely honest there really isn't any more that anyone can do to help, with how little information is available. It seems you've tested all the easy stuff, so at this point either start replacing components like the PSU or motherboard until the problem goes away, or start RMAing stuff until the problem goes away. It sucks, but I don't think it would be possible to pinpoint the issue based on the current information.

i agree def don't need 32gb of ram unless you specifically want it for after effects or something ram intensive

They're not in English (one location probably received review samples earlier than others) but here are the videos:
 
These review samples contain:
Noctua NH-U12S AM4-Ready CPU Cooler The AMD Ryzen 7 1800X CPU itself 16GB of Corsair Vengeance LPX DDR4 RAM Gigabyte AX370-Gaming 5 Motherboard The Ryzen box looks really nice imo. 
That said, we now know that AMD's flagship 1800X doesn't come with a cooler. This is, of course, because people who buy this processor are more likely to overclock it. (Hence the Noctua aftermarket cooler). Non-X CPUs are most likely going to come with the 'Wraith-Spire' coolers, which have RGB lighting!
And now we wait for the reviews.
 
 
 

I am not running active directory. Right now it is acting only as a file server

That would work much better, I don't know how I didn't think of that lol. I even have a spare switch I could use. Thanks!