I've had Cisco UCS C240s, and 220s, M3s, M4s, M5s and even M6s. Those things pretty much don't complain about what you put in them. Fan profile lockouts are an issue sometimes. There are special cards like VICs which have a compatibility matrix since they are configured only in the IPMI. But generally, I haven't run into too many issues with 3rd party cards.
I don't know how much of my experience translates to the S3260 though. And that triggered something in my brain. I had remembered seeing similar systems before.
It's seems it's the spiritual successor of the C3160/C3260, which also had all sorts of problems with various things.
This offer has expired. Even though the seller, deals2day-364, is selling more wither other configurations, AVOID THIS SELLER AT ALL COSTS! They have shipped units completely mis-configured, and missing many drives. Seller has completely ghosted ANYONE who bought a custom build and has NOT...
forums.servethehome.com
In that thread there may be interesting information pertaining to our situation here.