A couple of purchases (and days) later, I had new-to-me networking cards and active optical DACs to replace the copper wires ...

DAC is great in isolated setups, but once you get too dense/too much stuff you increase the chances of noise issues. They are copper electrical cables like any other so they have crosstalk etc ...

Supported SFP/SFP+ transceivers 10GBASE-Lr 1310-nm SFP+ (LC) for up to 10 km over SMF ... It won't work with several generic DAC cables I have that work just fine with a ProCurve and a TP-Link.