JTL yeah, sourcing the actual Intel card variants is hard in this case - they only made them for the initial series (770/750) and while a 750 can still be had (for ~$200) the 770 is all back stock or used and will run double that amount easily. The 580 never had a reference board, and it's not clear the 380 did either, so I was curious what brand 380 eDenon-2 had since that VBIOS would most likely be "safe".
He says it's Gunnir, which is unfortunately an APAC-exclusive brand. My options to get it in the USA are limited. So I'm going to grab an Intel reference board 750 and keep my fingers crossed. It'll run me $239 from Amazon, which is a bit of a premium, but worth it if I can use it for a few years without pain. I could grab one locally for $200 (for an unopened box model) or even less on the secondhand market. But at Amazon I can return it...